High water content, low viscosity, oil continuous microemulsions and emulsions, and their use in cleaning applications

An emulsion, which upon standing at 25.degree. C. forms at least two phases wherein one phase is an oil continuous microemulsion, comprising:

• A) water in an amount greater than 60 percent by weight and less than 95 percent by weight based on the total weight of the emulsion;
• B) an organic solvent or a mixture of two or more organic solvents, wherein the organic solvent or mixture of organic solvents are characterized as containing no more than 2 weight percent water at 25.degree. C. when the organic solvent is saturated with water in the absence of surfactants or other additives, and wherein the organic solvent or the mixture of two or more organic solvents are in an amount greater than 4 percent and less than 40 percent by weight based on the total weight of the emulsion;
• C) one or more ionic surfactants which are soluble in the one or more organic solvents, wherein the one or more ionic surfactants have a molecular weight in the range from 350 to 700, and wherein the one or more ionic surfactants are present in a total amount greater than 0.1 percent and less than 5 percent by weight based on the total weight of the emulsion;
• the emulsion characterized as being an oil continuous emulsion, wherein the emulsion has an electrical conductivity of less than 10,000Z microSiemens/centimeter when measured at use temperatures and a viscosity less than 40 centistokes as measured at use temperatures, wherein Z is represented by the following formula:
• Z=(1/30,000) (.phi..sub.w).sup.2 .SIGMA..sub.i A.sub.i m.sub.i, wherein .phi..sub.w represents the volume fraction of water in the microemulsion, i represents any electrolyte which is present in the microemulsion, A.sub.i represents the molar conductivity of electrolyte i and m.sub.i represents the molarity of electrolyte in the aqueous phase.