Ser. No. 09/019,340, filed February 5,1998.

Background of the Invention The invention relates to a dye-delivery system for introducing a leak detection dye into a fluid system.

Leak detection methods have been developed to analyze fluid systems, such as climate control systems (e. g., heating, cooling, ventilating, and air conditioning systems), hydraulics, engine oil systems, automatic transmission systems, fuel systems, brake systems, or radiator coolant systems, using dyes. Some methods employ emissive substances, such as, for example, fluorescent or phosphorescent dyes that are added to the refrigerants and/or lubricants of a climate control system.

Leaks can be detected by observing fluorescence of the dye at leak sites resulting from excitation of the dye with a light source having particular illumination characteristics, such as illumination wavelength or intensity. Suitable light sources for use in fluorescence detection emit light of wavelengths suitable to excite the dye and cause light emission from the dye, which is at a greater wavelength than excitation wavelength. In general, the dyes fluoresce brightly when excited by light in the 190 to 700 nanometer wavelength range. A variety of systems have been developed to introduce a leak detection dyes into air conditioning systems, including injectors that place solvent-based

solutions containing the dye into an operational air conditioning system.

Summary of the Invention In general, the invention features a dye-delivery composition for introducing a leak detection dye into a climate control system, an engine oil system, or a fuel system. The dye-delivery composition can be inserted directly into an assembled system, i. e., a climate control, fuel, or oil system, in a system component during assembly of the system, or during service of the system. The dye-delivery composition has a high weight percentage of dye, which can reduce the total amount of material that is introduced into the system to detect leaks.

In one aspect, the invention features a dye- delivery composition. The dye-delivery composition can include a lubricant and at least 3 weight percent of a leak detection dye. Preferably, the dye-delivery composition includes at least 5 weight percent of a leak detection dye.

In another aspect, the invention features a dye- delivery composition including a leak detection dye and an additive that is compatible with an engine oil or fuel system. The leak detection dye present in the composition includes a plurality of dye particles. The additive includes stearic acid, a wax, an engine oil, a lubricating oil compatible with an engine or fuel system, a hydrocarbon, a synthetic oil, or a polyolester. The dye-delivery composition includes at least 5 weight percent of the dye. The dye can be a naphthalimide. The composition can be a concentrate, a paste, or a suspension.

The dye-delivery composition can have a viscosity of at least 10 cps, preferably at least 500 cps, more preferably at least 3,000 cps, even more preferably at

least 10,000 cps, even more preferably at least 100,000 cps, and most preferably at least 500,000 cps. The dye- delivery composition can have a viscosity of between about 1 million cps and 4 million cps. Generally, a Brookfield RVT viscometer can be used for this measurement under conditions in which the dye-delivery composition exhibited fluid like behavior.

The dye-delivery composition can be thixotropic or semi-solid. A semi-solid composition is a deformable composition, such as a paste or gel. The dye-delivery composition can be a suspension of dye particles in the lubricant.

The leak detection dye can include a plurality of particles. The plurality of particles can be suspended in the lubricant. The plurality of particles has a distribution of particle sizes. Greater than 60 percent of the particles can have a particle size of less than 40 microns. Preferably, greater than 80 percent of the particles have a particle size of less than 40 microns.

Greater than 10 percent of the particles have a particle size of less than 5 microns. Preferably, greater than 40 percent of the particles have a particle size of less than 5 microns. More preferably, greater than 50 percent (e. g., greater than 60 percent) of the particles have a particle size of less than 5 microns. In preferred embodiments, greater than 80 percent of the particles have a particle size of less than 5 microns. In other embodiments, greater than 5 percent of the particles have a particle size of less than 10 microns, or greater than 20 percent of the particles have a particle size of less than 20 microns.

The dye-delivery composition can consist essentially of a lubricant and at least 3 weight percent of a leak detection dye.

Preferably, the composition includes at least 10 weight percent of the leak detection dye, more preferably at least 25 weight percent of the leak detection dye, and even more preferably at least 40 weight percent of the leak detection dye.

In preferred embodiments, the dye-delivery composition includes at least 50 weight percent of the leak detection dye. The dye-delivery composition can include at least 60 weight percent or at least 70 weight percent of the leak detection dye.

In another aspect, the invention features a method of manufacturing a dye-delivery composition. The method includes combining a lubricant and a leak detection dye to form a mixture, and mixing the mixture to form a suspension or a semi-solid material. The leak detection dye includes a plurality of particles which are suspended in the lubricant. Greater than 60 percent of the particles have a particle size of less than 40 microns.

Mixing can include high shear mixing.

In another aspect, the invention features a method of manufacturing a dye-delivery composition. The method includes the steps of combining a leak detection dye and an additive that is compatible with an engine oil or fuel system to form a mixture, and mixing the mixture to form a dye-delivery composition. The mixing can be by high shear mixing, roller mixing, or milling. The dye can be a micronized powder.

The leak detection dye includes a plurality of dye particles. The plurality of particles can be suspended in the additive. The plurality of particles has a distribution of particle sizes. Greater than 60 percent of the particles can have a particle size of less than 40 microns. Preferably, greater than 80 percent of the particles have a particle size of less than 40 microns.

Greater than 10 percent of the particles have a particle

size of less than 5 microns. Preferably, greater than 40 percent of the particles have a particle size of less than 5 microns. More preferably, greater than 50 percent (e. g., greater than 60 percent) of the particles have a particle size of less than 5 microns. In preferred embodiments, greater than 80 percent of the particles have a particle size of less than 5 microns. In other embodiments, greater than 5 percent of the particles have a particle size of less than 10 microns, or greater than 20 percent of the particles have a particle size of less than 20 microns.

Preferably, the composition includes at least 10 weight percent of the leak detection dye, more preferably at least 25 weight percent of the leak detection dye, and even more preferably at least 40 weight percent of the leak detection dye. In preferred embodiments, the dye- delivery composition includes at least 50 weight percent of the leak detection dye. The dye-delivery composition can include at least 60 weight percent or at least 70 weight percent of the leak detection dye.

In another aspect, the invention features a method of introducing a leak detection dye in a an engine oil or fuel system. The method can include placing a dye- delivery composition in a component of the system, for example, during manufacture or during service. Placing the dye-delivery composition in a component can include, for example, depositing the dye-delivery composition onto an inside or outside surface of the component or inserting the dye-delivery composition into the interior of the component. The method can include assembling the system after placing the composition into or onto the component. In other embodiments, the dye-delivery composition is placed in a component of an assembled system, for example, by injection.

In yet another aspect, the invention features a method of introducing a leak detection dye in a climate control system, an engine oil system, an automatic transmission system, a fuel system, a brake system, or a radiator coolant system. The method can include placing a dye-delivery composition in a component of the climate control system. Placing the dye-delivery composition in a component can include, for example, depositing the dye- delivery composition onto an inside or outside surface of the component or inserting the dye-delivery composition into the interior of the component. The method can include assembling the climate control system including the component. In other embodiments, the dye-delivery composition is placed in a component of an assembled climate-control system, for example, by injection.

The climate control system can be a mobile, stationary, window air conditioning system such as an automotive, portable, residential, or commercial air conditioning system, or any other hermetic system that employing a refrigerant and lubricant. The system can include a refrigerant. The refrigerant can include chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, carbon dioxide, ammonia, halogenated or ether derivatives of methane or ethane, or halogenated ether or cyclic derivatives of propane, butane, pentane, or other hydrocarbons. The system can also include a lubricant. The refrigerant, lubricant, or refrigerant- lubricant mixture can dissolve the leak detection dye and distribute it throughout the system. The leak detection dye is soluble in the refrigerant, or combinations of the refrigerant and lubricant.

The dye-delivery composition can be placed in a system, i. e., climate control, fuel, or oil system, or a component of a system. The composition can be placed in or on a portion of a component of the system. In an air

conditioning system, the component can be a liquid line receiver, a receiver drier, a filter drier, an accumulator, a compressor, a condenser, a high pressure discharge line, a discharge muffler, a liquid line heat exchanger, a filter pad, filter media, an expansion device (e. g., an expansion valve or orifice tube), a suction line, a suction muffler, an orifice tube, a hose line, an expansion valve, a fitting assembly, a filter assembly, or an evaporator.

A dye-delivery composition, including the leak detection dye and lubricant, can have a sufficiently high viscosity to allow it to be placed directly onto the system or a component of the system without dripping or otherwise running off of the component. For example, the composition can be thixotropic or semi-solid. A semi- solid composition is a deformable composition, such as a paste or gel. Likewise, a dye-delivery composition, including the leak detection dye and additive, can have a sufficiently high viscosity to allow it to be placed directly onto the system or a component of the system without dripping or otherwise running off of the component. For example, the composition can be thixotropic, semi-solid, or solid.

Introducing a leak detection dye as a dye-delivery composition during the assembly of the system, i. e., climate control, fuel, or oil system, can enable the system to be tested for leaks to provide a quality assurance tool prior to shipment of the system. It can also facilitate checking the system for leaks at a later time in the field without charging the system with additional leak detection dye. The dye-delivery composition can provide a simple way to insert dyes into, for example, an air conditioning system rapidly and cleanly, without needing to charge the system with refrigerant at the time of dye insertion. The dye-

delivery composition can provide a simple way to insert dyes into, for example, an engine oil or fuel system rapidly and cleanly. Installation during assembly also allows manufacturers to test products on site, permitting the rapid identification of leaks.

Insertion location, composition properties, and dye properties can be selected to improve cost, ease of insertion, cleanliness of handling, capital equipment costs, material waste, environmental impact, shelf life prior to insertion in the system, and chemical life once introduced into the system. The composition can be substantially compatible with known systems because the composition can include only the lubricant and the leak detection dye or the additive and the leak detection dye.

The dye-delivery compositions are easy to handle and use. Because the dye-delivery composition carries a high weight percentage of the dye, use of the composition can reduce the risk of contaminating the work environment with the dye, which can lead to erroneous leak detection.

In addition, the composition dissolves completely either in a mixture of lubricant and refrigerant or in oil or fuel. The dye-delivery composition can be essentially solvent-free and can be substantially free of impurities that could otherwise damage a climate control system.

The composition can consist essentially of the leak detection dye and the lubricant. The dye-delivery composition can be essentially solvent-free and can be substantially free of impurities that could otherwise damage a system. Small amounts of other additives such as surfactants (e. g., siloxanes) can be included in the composition.

Additional features and advantages of the invention will become apparent from the detailed

description of the preferred embodiments of the invention.

Description of the Preferred Embodiments A dye-delivery composition includes a leak detection dye and a lubricant. Preferably, the dye- delivery composition can consist essentially of the leak detection dye and the lubricant. Alternatively, the dye- delivery composition includes a leak detection dye and an additive. Preferably, the dye-delivery composition can consist essentially of the leak detection dye and the additive. The composition can be characterized as a concentrate, a paste, a suspension of dye in the lubricant or additive, or a solid structure.

The leak detection dye can include a naphthalimide, a perylene, a coumarin, a thioxanthane, or a derivative thereof, or other dye compatible with a system, e. g., a climate control, an engine oil, or fuel system. The composition can contain a high proportion (e. g., greater than 50%) of leak detection dye.

A suitable lubricant and additive can include an engine oil, a lubricating oil compatible with an engine or fuel system, a synthetic oil, a polyalkylene glycol, a polyolester, a mineral oil, a polyvinyl ether, an alkylbenzene, or another synthetic lubricating material.

The engine oil can be 5W30, or any other engine oil. Suitable polyalkylene glycol or polyol ester lubricants include, for example, Emery 2927a, Mobil Arctic EAL 68, Union Carbide UCON 488 Refrigeration Lubricant, Union Carbide UCON MLX-1197 Experimental Lubricant, Union Carbide 50-HB5100, Motorcraft YN-12B, Ford PAG, Chrysler PAG, or any other automotive PAG.

UCON 488 is a polyalkylene glycol having a viscosity of about 133 centistokes at 40°C. Union Carbide 50-HB5100 is a polyalkylene glycol having a viscosity of about 1020

centistokes at 40°C. Motorcraft YN-12B is a polyalkylene glycol having a viscosity of about 56 centistokes at 40°C. The viscosity of the lubricant can affect the viscosity of the dye-delivery composition.

Suitable additives and dyes are soluble in the engine oil or the fuel of the system. Since typical engine oil and fuel systems are anhydrous, the preferred additive is an organic compound. The additive is compatible with the components of the engine oil or fuel system and does not react adversely with the engine oil or fuel, such as gasoline, propane, diesel fuel, other hydrocarbons, ethanol, hydroxylated fuels, natural gas, or esters, over a wide range of temperature and pressure conditions encountered in use. The solubility and compatibility of the additive with the components of the engine oil or fuel system can lead to rapid dissolution properties of the structure. The additive can be a lubricant, in the case of a concentrate, a paste, or a suspension, or a binding agent, in the case of a solid structure.

A binding agent can include a wax, a fatty acid, a fatty alcohol, a fatty acid ester, a resin composition, a polyol ester, a polyalkylene glycol, or a hydrocarbon, or mixtures thereof. The resin composition can include beeswax, carnauba wax, an automotive polishing wax, floor polish, or a polyethylene glycol. The wax can be a paraffinic wax, a naphthenic wax, a synthetic wax (e. g., paraffinic raffinate), a stearic wax, a natural wax, or any other wax-like material that is compatible with engine oil or fuel. The polyol ester can be a pentaerythritol ester, a trimethanol propane ester, a triglyceride, diglyceride, or a complex polyol ester.

The fatty acid, fatty alcohol, fatty acid ester, and polyol esters such as triglycerides and diglycerides have saturated or unsaturated C4-C18 chains. The esters can be

Cl-Cl8 alkyl esters. In particular, the binding agent can include stearic acid, methyl stearate, coconut oil, tricaprin, hydrenol, Lorol (C16), Lorol (C18), cocoa butter, methyl laurate, methyl myristate, coconut fatty acid, methyl coconate, lauryl alcohol, cetyl alcohol, peanut oil, hydrogenated coconut oil, and hydrogenated peanut oil. Tricaprin is a C12 compound. Preferred binding agents include stearic acid, methyl stearate, coconut oil, and coconut fatty acid. A variety of binding agents are available, for example, from Aldrich Chemical Co., Abitec Corporation, Henkel, Universal Preserve-A-Chem. Suitable lubricants include system lubricants, such as polyalkylene glycol or polyol ester lubricants. The solid structure can contain between 0 and 10 weight percent binding agent, preferably between about 0.1 and about 5 weight percent, and more preferably between 2 and 4 weight percent.

Several techniques are available for preparing the dye-delivery composition. Generally, particles of the leak detection dye are combined with the lubricant or additive to form a mixture. The mixture can be processed to form a concentrate, a paste, a suspension, or a solid structure. The particles are ultimately suspended or dispersed in the lubricant or additive by mechanical means. The mechanical mills can reduce the particle sizes of the dye during the mixing process. The smaller particle sizes can lead to more stable suspensions. The smaller particles can be re-dispersed readily in the lubricant by agitation. In general, the concentrate, suspension, or paste can be formed from particles suspended or dispersed in the lubricant or additive by mechanical means. The process involves steps that thoroughly mix the two components of the composition while decreasing the particle size of the dye. For example, the mixture can be subjected to high shear

mixing conditions in an impeller mill or blender such as an emulsifier or a homogenizer. Other mills that can be used to disperse the solid dye particles in the lubricant include ball mills, stirred media mills, vibratory mills, multiple roll mills (e. g., a three roll mill or a five roll mill), or ultrasonic mills.

Additionally, the particle size distribution of the dye powder can be reduced prior to mixing the dye with the lubricant or additive. The smaller particles can be re-dispersed readily in the additive by agitation.

The particle size reduction can be achieved using, for example, a crusher, pulverizer, grinding mill, attrition mill, ball mill, sand mill, bead mill, chaser mill, jar mill, hammer mill, impact grinding mill, air jet mill, or micronizer. For example, dye powders can be processed by methods described in"Remington's Pharmaceutical Sciences,"14th Edition, Mack Publishing Co., 1970, which is incorporated herein by reference. Particular mixing conditions are described, for example, in U. S. Ser. No.

09/065,007, filed April 23,1998 and U. S. Ser. No.

09/019,340, filed February 5,1998, each of which is incorporated herein by reference.

The dye-delivery composition can be a suspension, paste, or semi-solid material. The dye-delivery composition can be thixotropic.

In general, solid structures of the dye-delivery composition can be formed by thorough mixing via grinding, milling, or other granulation methods which provide mixtures that can be molded or compacted into the solid structures. After mixing, the mixture is formed into the dye-delivery structure by extrusion, compaction, molding, heating, or cooling. The mixture can be compacted by supplying pressure using mechanical press or manual means. The resulting structure can take the form of a tablet, a briquette, a sphere, a disc, a bead, a

pellet, or a cylinder. The dye-delivery structure can be formed with maximum surface area to assist in dissolution by providing enhanced or embossed surfaces or structures with one or more holes or openings therethrough.

The solid structure is compacted to a degree sufficient to avoid damage during normal handling and storage and at the same time being of a density sufficient to facilitate dissolution when placed into the system to aid in the detection of leaks. The solid structures have good mechanical strength, for example, to impact and vibration, are not too brittle, and are capable of rapid dissolution. In general, harder structures have slower dissolution rates. In other words, the pressure applied to form the structure by compaction is selected to increase hardness of the structure, while maintaining good dissolution rates and solubility for the structure.

Hardness of the structure can be determined using Tablet Hardness Tester, Model 900-539-001, available from DT Industries, Stokes Division, Bristol, PA. The hardness of the structure can be between 2 and 25 kg, preferably between 3 and 15 kg using this test. The hardness of tablets including a naphthalimide leak detection dye, 2-4% of a binding agent, and 0-2% of a lubricant varied between 3.5 kg and 9.5 kg.

Solubility rate of the structure can be determined by a percent solubility test. First, the structure is weighed and placed into a test tube with a known volume of a liquid component of the engine oil or fuel system.

The tube is then placed onto an oscillating test tube rack and rotated for 2 hours. After two hours, the structure is removed from the oscillating rack and allowed to air dry. The structure was reweighed and the percent solubility was calculated according to the formula:

% solubility = (initial weight-final weight)/initial weight The percent solubility of the structure, according to the test method, can be greater than 50 percent, preferably greater than 60 percent, more preferably greater than 75 percent, and most preferably greater than 85 percent. The percent solubility of tablets including a naphthalimide leak detection dye, 2-4% of a binding agent, and 0-2% of a lubricant varied between 49 percent and 89 percent, according to the above-described test method.

The dye-delivery composition can be placed into a climate control system or an engine oil or fuel system.

The dye-delivery composition need not be immobilized in the system. Suitable locations can provide a desired dissolution rate of the dye-delivery composition. In particular, the composition can be placed on the inside or outside of a component of a system. The concentrate, suspension, or paste can be dispensed into the system by, for example, a syringe or other metering device. The solid structure can be added as a unit into the system.

The concentrate, paste, or suspension can have a thickness or viscosity sufficient to prevent dripping of the dye from the component after it is dispensed.

In an engine oil or fuel system the dye-delivery composition can be placed in a component of the system.

The component can be an oil filter, an engine block, an oil pan, a fuel tank, or a fuel filter. The composition can be placed into the component before assembly of the system, or after assembly of the system. For example, the composition can be placed in an oil filter that is added to an existing engine system, such as when a system is being serviced. Alternatively, the composition can be added to a component of the engine oil system at the

point of manufacture or remanufacture. For example, a composition can be introduced into an oil filter or onto the bottom of oil filter for instant dye circulation.

The composition can also be injected into the oil pan or into the top part of the engine.

The dye-delivery composition can be placed into an air conditioning system. In particular, the composition can be placed on the inside or outside of a component of an air conditioning system. The composition can be dispensed into the system by, for example, a syringe or other metering device. The composition can have a thickness or viscosity sufficient to prevent dripping of the dye from the component after it is dispensed. The composition can contain a high proportion of leak detection dye.

The location for placement of the composition in the system can be selected to increase the dissolution rate of the composition. For example, components that have a greater flow of refrigerant or a greater flow of lubricant can be selected to provide more rapid dissolution rates. Similarly, components that contain the refrigerant or the lubricant at higher temperatures can be selected to provide more rapid dissolution rates.

Suitable locations for placement of a dye-delivery composition in an air conditioning system can include a liquid line receiver, an accumulator, a receiver dryer, a filter drier, a liquid line heat exchanger, a filter pad, filter media, a compressor, a condenser, a high pressure discharge line, a discharge muffler, an orifice tube, a suction line, a hose line, a expansion valve, a fitting assembly, an access fitting, a charging port, a reservoir, or an evaporator. The dye-delivery composition need not be immobilized in the system. The dye-delivery composition can be adsorbed onto a material.

Each of the suitable locations can provide a desired

dissolution rate of the dye composition. For example, suitable locations can have higher operating temperatures than other locations, leading to more rapid dissolution of the composition.

After placing the composition into a system, e. g, an air conditioning, fuel, or oil system, the system is operated to circulate the refrigerant and lubricant. The circulating refrigerant, lubricant, or refrigerant- lubricant mixture dissolves the leak detection dye, dispersing it throughout the system. Once dissolved, the dye content of the system can be below about 1.0, preferably less than 0.5 percent, and more preferably less than about 0.1 percent. After the dye has been allowed to circulate within the system, system components, joints, fittings, or attachments can be examined for leaks with a light source having a light emission wavelength from 190 nanometers to 700 nanometers. The presence of a leak can be determined by the presence of a colored visual indication, such as fluorescence or other emission, that can be detected after excitation with the light from the light source.

The following examples are illustrative, but not limitive, of the invention.

Examples A number of compositions were prepared by mixing powdered leak detection dye with a lubricant. In Examples 1-6, the compositions were prepared by homogenization of the mixture using a mixer/emulsifier.

In Examples 7-11, the compositions were prepared by mixing followed by roll milling. The viscosities and particle size distributions of the compositions were also examined. In Examples 16-18, a number of compositions were prepared by mixing powdered leak detection dye with an additive.

Examples 1-6 Solvent Yellow 43 dye powder (CAS 19125-99-6) was combined with a lubricant at dye concentrations of 40 weight percent, 50 weight percent, and 60 weight percent to form a mixture. The lubricants used to prepare these compositions were UCON 488 Refrigeration Lubricant, UCON MLX-1197 Experimental Lubricant, and Motorcraft YN-12B Refrigerant Compressor Oil. 200 grams of dye powder and 300 grams of lubricant were combined to form the 40 weight percent mixture; 300 grams of dye powder and 300 grams of lubricant were combined to form the 50 weight percent mixture; and 300 grams of dye powder and 200 grams of lubricant were combined to form the 60 weight percent mixture.

Each mixture was processed using a Ross Mixing ME 100LC Model laboratory mixer/emulsifier (Charles Ross & Son Company, Hauppauge, NY). Processing was carried out by agitation using the highest shear mixing blade.

Processing times were dependent on dye concentration.

The 40 weight percent mixtures were agitated for 30 minutes, the 50 weight percent mixtures were agitated for 60 minutes, and the 60 weight percent mixtures were agitated for 90 minutes. The mixer speed was adjusted to create a vortex which just exposed the top of the mixing blade which did not splash material out of the mixing vessel. The mixer speed increased with dye concentration and was generally between about 2000 and 4000 rpm. The composition formed by the process was a suspension of dye in the lubricant. Compositions of particular examples of concentrates prepared using the mixer/emulsifier are shown in Table I.

Table I

Example Lubricant Type Wt% Lubricant Wt% Dye Type UCON MLX-1197 50 50 Suspension 2 UCON MLX-1197 40 60 Suspension 3 UCON 488 50 50 Suspension 4 UCON 488 40 60 Suspension 5 MOTORCRAFT YN-12B 50 50 Suspension 6 MOTORCRAFT YN-12B 60 40 Suspension In general, the compositions prepared by homogenization thickened and remained in suspension longer with increased dye concentration. The 40 weight percent composition remained in suspension for about 1-2 days, the 50 weight percent and 60 weight percent composition remained in suspension for about 3-5 days.

After about 3-5 days, a layer of lubricant was observed at the top of the composition. The dye was easily resuspended by manual agitation. Examples 5 and 6 appeared to be more viscous than Examples 1-4.

Examples 7-11 The formulations of Examples 7-11 were prepared by combining Solvent Yellow 43 dye powder with a lubricant at dye concentrations of 60 weight percent and 70 weight percent to form a mixture. The lubricants used to prepare these compositions were UCON 488 Refrigeration Lubricant and 50-HB5100 from Union Carbide. The composition of Example 7 was prepared in a 2 pound batch; the compositions of Examples 8-11 were prepared in 6 pound batches. Compositions of particular examples of dye-delivery compositions prepared by mixing followed by roll milling are shown in Table II.

Table II

Example Lubricant Type Wt% Lubricant Wt% Dye Type 7 50-HB5100 30 70 Paste 8 50-HB5100 40 60 Paste 9 50-HB5100 40 60 Paste 10 UCON 488 30 70 Paste 11 UCON 488 40 60 Paste Example 7 was mixed by hand until relatively homogenous. The material was then passed twice through a Ross Three Roll Mill (Charles Ross & Son Company, Hauppauge, NY). The material was a smooth paste showing excellent dispersion when a piece of material was pressed between two glass slides.

Example 8 was mixed in a Ross LDM 2 gallon Planetary Mixer (Charles Ross & Son Company, Hauppauge, NY) and subjected to a vacuum of about 29.8 inches of Hg at a mixing speed of about 78 rpm for about ten minutes.

The material was then passed through a Ross Three Roll Mill. Six pounds of material passed through the mill in 15 minutes.

Example 9 was a portion of Example 8 that was passed through the Ross Three Roll Mill a second time.

Example 10 was mixed in a Ross LDM 2 gallon Planetary Mixer and subjected to a vacuum of about 29.8 inches of Hg at a mixing speed of about 48 rpm for about ten minutes. The material was then passed twice through a Ross Three Roll Mill.

Example 11 was mixed in a Ross LDM 2 gallon Planetary Mixer and was subjected to a vacuum of about 29.8 inches of Hg at a mixing speed of about 72 rpm for about ten minutes. The material was then passed once through a Ross Three Roll Mill.

The resulting compositions were paste-like materials.

The viscosities and particle size distributions in the compositions of Examples 1-11 were examined. The viscosities were measured with a Brookfield RVT viscometer. T-bar spindles with a Helipath stand were used to measure viscosities of the semi-solid samples; a rotation rate (i. e., 1 RPM) was used for this measurement at which the semi-solid sample exhibited fluid behavior at low shear stress. Standard spindles were used for the liquid samples. The sample viscosities are listed in Table III.

Table III Example Spindle RPM Dial Reading Multiplier Viscosity 1 #5 20 76. 5 50 3825 cps 2 #5 20 31 200 6200 cps 3 #5 20 28-28. 5 200 5600-5700 cps 4 #5 20 82-85 200 16400-17000 cps 5 #5 20 19.5 200 3900 cps 6 TF 20 15.5 2000K 31000 Kcps 7 TF 1 19-21 100K 1900-2100 Kcps 8 TF 1 14. 5-15 100K 1450-1500 Kcps TF 1 32 (35-20) 100K 3200 Keps 10 TF 1 29. 5 100K 2950 Kcps TF 1 20. 5 100K 2050 Kcps The viscosity of the compositions prepared by roll milling was higher than the homogenized material. The viscosity of the composition increased when the material was passed through the mill a second time. The viscosity generally increased as the dye content of the composition increased.

The particle size distributions were determined by ocular examination of a series of slides on which the samples were smeared. The slides were photographed at 400 times magnification. The photographs were placed under a calibrated grid. The size and number of particles were tabulated. The particle size distributions are listed in Table IV.

Table IV

Example 1-5 5-10 10-20 20-40 40+ micron micron micron micron micron 1 51 % 9 24 6 9 2 18 % 74 7 3 44 % 38 % 7 % 11 % 4 42 0 350 13 % 8 0 2 % 54 % 21 % 14 % 11 % 6 6 % 23 % 63 % 8 % 7 85 % 14 % 1 % 8 44 % 50 % 6 % 9 93 % 7 % 10 99.7 % 0.3 % 11 99 % 1 % In general, roll milling of the composition resulted in smaller particle sizes and narrower distributions of particle sizes.

Examples 12-15 Solvent Yellow 43 dye powder (CAS 19125-99-6) was micronized using an air jet mill. The resulting micronized dye powder had a particle size distribution in which all of the particle sizes were less than 11 microns, with an average particle size of 2.17 microns.

The micronized dye powder was combined with a lubricant at dye concentrations of 20 weight percent and 3 weight percent to form a mixture. The lubricants used to prepare these compositions were 50-HB5100 from Union Carbide, an alkylbenzene lubricant having a viscosity of about 10 centistokes at 40°C, a hydrocarbon oil having a viscosity of about 10 centistokes at 40°C, and an Idemitsu PAG having a viscosity of about 44 centistokes at 40°C. The materials were mixed using a mortar and pestle to form a suspension. Compositions of particular examples of dye-delivery compositions prepared using the micronized dye powder are shown in Table V.

Table V

Example Lubricant Type Wt% Lubricant Wt% Dye Type 12 50-HB5100 80 20 Suspension 13 Idemitsu PAG 97 Suspension 14 alkylbenzene 97 3 Suspension 15 hydrocarbon oil 97 Suspension Examples 16-18 Solvent Yellow 43 dye powder (CAS 19125-99-6) was micronized using an air jet mill. The resulting micronized dye powder had a particle size distribution in which all of the particle sizes were less than 11 microns, with an average particle size of 2.17 microns.

The micronized dye powder was combined with a 10W40 engine oil at dye concentrations of 30 weight percent, 60 weight percent, and 70 weight percent. The materials were weighed and placed on a flat stainless steel surface. The engine oil was added and the materials were milled by hand using a spatula against the flat surface.

With time, more oil was gradually added. Each batch was approximately 1 pound in size and took about 30 to 45 minutes to mill by hand. Examples of compositions prepared using the micronized dye powder are shown in Table VI.

Table VI Example Additive Type Wt% Additive Wt% Dye Type 16 1OW40 engine oil 70 30 Thick flowable liquid 17 10W40 engine oil 40 60 Thick paste I 18 10W40 engine oil 30 70 Thick paste I

The dye-delivery composition had a high enough concentration of dye to yield sufficient fluorescence when excited with a UV lamp to permit satisfactory leak detection when about one quarter ounce of Example 16 was placed into about 4 quarts of engine oil. The light yellow color and strong green fluorescence of the naphthalimide dye allows for more rapid and effective leak detection.

The composition of Example 16 exhibits good stability when placed into an engine oil system of a vehicle. The composition was added to the system by introducing the composition of Example 16 through the oil filler cap of the engine. The engine was run for about five minutes to disperse the dye in the oil. The engine of the vehicle was run for a test period of about 40 hours. After running for the test period, the dipstick was removed and a strong fluorescence of the oil on the dipstick was observed.

Other embodiments are within the claims. For example, the dye-delivery composition can be adsorbed onto a substrate material. For instance, the dye- delivery composition can be placed on a porous or fibrous material that can adsorb the lubricant from the composition, thereby converting the composition into a semi-solid dye-delivery composition. Additionally, the composition can include small amounts of a silicone or a phosphate ester. The compositions can be used to introduce leak detection dyes into an automatic transmission system, a hydraulic system, a machine lubricating system, a brake system, or a radiator coolant system.

What is claimed is: