Automotive engine cooling system stop-leak formulation

Abstract

The present invention relates to an automotive engine cooling system stop-leak formulation for repairing leaks in an engine cooling system, is compatible with common coolant antifreeze types and is capable of maintaining the repair after draining and re-filling the coolant. The automotive engine cooling system stop-leak formulation comprising a polymeric resin and a particulate package, wherein the particulate package comprises a first natural fibre having a first fibre length and a greater amount of a second natural fibre having a second fibre length.

Claims

1. An automotive engine cooling system stop-leak formulation comprising a polymeric resin and a particulate package, wherein the particulate package comprises a first fiber having a first fiber length and a greater amount of a second fiber having a second fiber length, wherein the first fiber length is in the range 50 m to 500 m and the second fiber length is in the range 1 to 25 m.

2. The automotive engine cooling system stop-leak formulation of claim 1 wherein the weight average first fiber length is 100 m to 300 m and the weight average second fiber length is 10 m to 20 m.

3. An automotive engine cooling system stop-leak formulation comprising a polymeric resin and a particulate package, wherein the particulate package comprises a first fiber having a first fiber length and a greater amount of a second fiber having a second fiber length, wherein the weight ratio of the first to the second fiber is from 1:2 to 1:12 and the second fiber is longer than the first fiber.

4. The automotive engine cooling system stop-leak formulation of claim 3 in which the weight ratio of the first fiber to the second fiber is between 1:4 and 1:8.

5. An automotive engine cooling system stop-leak formulation comprising a polymeric resin and a particulate package, wherein the particulate package comprises a first fiber having a first fiber length and a greater amount of a second fiber having a second fiber length, wherein the first fiber is wood flour and has a particle size distribution such that at least 90% are retained by a 100 m screen but less than 1% are retained by a 600 m screen.

6. An automotive engine cooling system stop-leak formulation comprising a polymeric resin and a particulate package, wherein the particulate package comprises a first fiber having a first fiber length and a greater amount of a second fiber having a second fiber length wherein the fibers are the natural fibers wood flour and oilseed meal.

7. The automotive engine cooling system stop-leak formulation of claim 6 in which the oilseed meal is an expelled linseed meal.

8. An automotive engine cooling system stop-leak formulation comprising a methyl methacrylate copolymer polymeric resin and a particulate package, wherein the particulate package comprises a first fiber having a first fiber length and a greater amount of a second fiber having a second fiber length.

9. The automotive engine cooling system stop-leak formulation of claim 8 in which the methyl methacrylate copolymer polymeric resin selected from a methyl methacrylate-ethyl acrylate copolymer or methyl methacrylate-butyl acrylate copolymer.

10. The automotive engine cooling system stop-leak formulation of claim 8 in which methyl methacrylate copolymer polymeric resin has an Mz average molecular weight between 100 000 and 400 000 Daltons.

11. The automotive engine cooling system stop-leak formulation of claim 8 in which the polymeric resin has a glass transition temperature between 30 C. and 80 C.

12. The automotive engine cooling system stop-leak formulation of claim 8 in which the weight ratio of the polymeric resin to the combined first and second fibers is between 1:0.5 and 1:1.5.

13. A method of repairing a coolant leak comprising introducing the automotive engine cooling system stop-leak formulation of claim 1 into an automotive engine cooling system and running the engine.

14. The method of claim 13 in which the automotive engine cooling system comprises a monoethylene glycol based cooling fluid.

Description

DETAILED DESCRIPTION

(1) A stop-leak formulation 15MN002 was blended according to the following formula:

(2) TABLE-US-00001 TABLE 1 Ingredient % w/w Water 88.07 Buffer, trisodium citrate 1.00 Sodium hydroxide 0.14 Expelled linseed meal 2.82 Acrylic resin copolymer in solvent 7.00 Wood flour 0.50 Antifoam 0.20 Antimicrobial 0.25 Colourant 0.02

(3) A stop-leak formulation is blended into water, using a ratio of wood flour:expelled linseed meal of 1:5.6 for the particulate package and a ratio of 1:1.05 acrylic resin copolymer to particulate package.

(4) Thermoplastic resins to use in this embodiment were selected on a number of different criteria including block copolymer combination, solubility parameters, available form and solvent systems, glass transition temperature, molecular weight, density.

(5) In these tests the resin was provided as specified, Form No. 884-000174-0612-NAR-EN-CDP being a methyl methacrylate-butyl acrylate copolymer of Mz 250,000 and Tg 50 C., containing polymer 45% solids in toluene. As the coolant vessel cools and the resin reverts back towards its glass state the packing is sufficiently regular to maintain a seal even though the seal becomes increasingly brittle particularly in low molecular weight polymers. A resin that is too brittle may rupture when pressure is introduced to the vessel.

(6) The following comparative formulations were also tested:

(7) TABLE-US-00002 TABLE 2 Comparative 1 Comparative 2 Comparative 3 Ingredient % w/w % w/w % w/w Water 88.07 88.07 88.07 Buffer, trisodium 1.00 1.00 1.00 citrate Sodium hydroxide 0.14 0.14 0.14 Expelled linseed meal 3.32 0.0 2.82 Resin as specified 7.00 7.00 0.00 Polyacrylic acid 0.00 0.00 7.00 Wood flour 0.00 3.32 0.50 Antifoam 0.20 0.20 0.20 Antimicrobial 0.25 0.25 0.25 Colourant 0.02 0.02 0.02

(8) Polyacrylic acid, Tg 109 C. was of equivalent Molecular weight and of the same solution concentration as the Resin as specified. In the present invention glass transition temperature can be determined using ASTM E1356-08(2014) Standard Test Method for Assignment of the Glass Transition Temperatures by Differential Scanning Calorimetry.

(9) The formulations were then subject to testing to simulate the conditions in a vehicle coolant system.

(10) Test Method

(11) Development formulations together with a suite of competitor products were evaluated using a stop-leak additives performance test method from the American Society for Standards and Materials, ASTM D3147-06.

(12) The ASTM D3147-06 method comprises providing a rectangular stainless steel 12 to 13.5 litre vessel designed to contain up to 140 kPa pressure. Heaters and pumps are provided to enable testing over a range of temperatures and pressures. Test plates constructed of solid brass are attachable to the reservoir with a gasket. Test plates may have slits 12.7 mm long and various widths. Test plates may have three holes each of the same size, or nine holes of various sizes. Test are defined to measure the leakage through the holes after adding the stop-leak product to coolant, simulating the conditions of operating a car engine, such as running at a temperature of between 84 C. and 92 C. and a pressure of between 88 kPa and 118 kPa

(13) The sealing test used to assess the present invention was broken down into six steps, based on the ASTM D3147-06 standard. A stainless steel vessel, circulation pump and heater are provided, and connected to pressurisation equipment. Along adjacent faces of the vessel are spaces in which interchangeable brass plates with holes or slots may be inserted. Plates with a hole size of 0.762 mm (0.030) and slots of 0.254 mm (0.010) were chosen for the final testing. Plates having holes and slots of these sizes were chosen as these are the largest holes advisable according to the ASTM that a stop-leak product should seal without the possibility of causing harm to a vehicle's cooling system. As some products could not pass the test at these sizes, they were also tested with a smaller hole size of 0.508 mm (0.020).

(14) Step 1 comprises adding the coolant and the stop-leak formulation, 214 ml to 12 l of coolant (monothylene glycol and water 50/50 by volume) to the vessel and then heating to about 88 C. The coolant and formulation mixture is circulated using a pump.

(15) Step 2 comprises pressurising the test sample to 10315 kPA (152 psi) while maintaining the temperature and circulation for two hours.

(16) Step 3 comprises allowing the sample to cool with no circulation while maintained at a test pressure of 10315 kPA (152 psi) for a duration of 12 to 20 hours to simulate overnight conditions.

(17) Step 4 comprises releasing the pressure, then reheating the sample with the circulating pump turned on, and once the temperature reaches 88 C., pressurising the vessel to 10315 kPA (152 psi) again.

(18) Step 5 comprises allowing the system to cool to room temperature.

(19) Step 6 comprises pressurising the system again and running the system for a further hour.

(20) Sealing performance was evaluated by recording lost fluid together with various other parameters and observations recorded in a general format, including volume of fluid loss and ambient and solution temperatures as described by ASTM D3147-06. In order to PASS a formulation must maintain a minimum working volume of 4.5 litres throughout the duration of the test.

(21) Furthermore, a no-harm test used in the ASTM standard comprising two aspects was carried out. The first is a sieve test, the sample coolant and formulation mixture is screened through an 850 m sieve both before and after the test, and evidence of gumming, gelling or visible particles that may block engine components such as radiator tubes are considered to be a failure.

(22) The second is a blockage test, which is carried out by replacing the plates used in the performance test to larger ones representative of the size of the coolant pathways or the radiator. These slots are 0.635 mm wide and 12.7 mm long. To pass this test there must be no seal formed on the slit or holes, allowing the coolant to drain from the system freely. This is therefore representative of the formulation not blocking any pathways in the cooling system.

(23) Test Results

(24) The present invention performed to a higher level than any current product on the market. The new formula exhibited a 100% pass rate on the ASTM D3147-06 sealing test and maintained an effective seal after 3 subsequent drain and re-fill exercises.

(25) In the following table the results of testing formulation 15MN002 and a number of products available on the market at the time of testing are compared.

(26) TABLE-US-00003 TABLE 1 Test results using plates with a hole size of 0.762 mm (0.030) and slots of 0.254 mm (0.010). Number of Number of Designation Tests Passes Pass rate Note 15MN002 36 36 100% Bars Leak TM 3 1 33% smaller holes only passed Carlube TM 4 2 50% smaller holes only passed K-Seal TM 7 1 14% Wurth TM 1 0 0% Wynns TM 3 1 33% Comparative 1 1 0 0% Comparative 2 1 0 0% Comparative 3 1 0 0%

(27) Table 1 shows that none of the existing markets could reliably pass the ASTM D3147-06 test using plates with a hole size of 0.762 mm (0.030) and slots of 0.254 mm (0.010). Further, the data shows that the combination of the two natural fibres used in combination with the preferred polymer type is better than the fibres were when used individually.

(28) Formula 15MN002 passed this test 100% of the time. The formula also passed the same test after four refills of the test vessel with fresh coolant, indicating that it exceeds the requirements for a permanent repair as defined in this specification.

(29) The formula also passed the important no-harm test, designed to ensure the small bore holes within a cooling system remain unblocked when a cooling system stop-leak product is used. In this test, the formula must allow free draining of the coolant. The new formula produced a PASS, in good fashion with laminar flow.

(30) The competitor products were unable to reliably pass the ASTM D3147-06 sealing test.

(31) The present invention offers an improve stop-leak products which seal holes in engine cooling systems.

(32) The present invention can be practically applied in the form of a new product that will serve to function as a superior engine cooling system leak repair.

(33) The test results demonstrate that the new formula is superior in all aspects that were tested. Furthermore, the seal can be regarded as permanent based on the definition within this document. By permanent, in this application, it is taken to mean that the sealing effect persists even after three replacements of coolant in a system following a repair.