Surfactants are used in a variety of detergents throughout industry and in the home in applications where it is desirable to reduce the surface and interfacial tension of water so that it will easily wet the surfaces of solid materials and promote cleaning. In order to meet the many demands placed upon these materials by reason of their varied applications and uses, detergents are produced in various forms and have many different combinations of properties. For instance, detergents may be solids or liquids; they may be anionic, cationic, non-ionic, or amphoteric; they may vary in their degree of water solubility; and they may vary considerably in their resistance to degradation by bacterial attack.
Non-ionic liquid surfactants have found particular application for use in aqueous liquid heavy-duty clothes washing compositions and powdered compositions for washing clothes.
In recent years a number of changes have occurred with respect to the requirements of surfactants for detergent compositions. For instance, the temperature at which clothes are washed has significantly decreased over the years in view of the concern for energy conservation. For instance, some twenty to twenty-five years ago in the United States clothes were washed in temperatures of about 140.degree. F. to about 160.degree. F. However, today, the highest temperatures used for washing clothes in the United States is about 120.degree. F. In particular, hot water washing is usually considered to be about 100.degree. F. to about 120.degree. F., warm water washing is usually at about 75.degree. F. to 90.degree. F., and cold water washing is from about room temperature to about 75.degree. F. This significant change in the temperature of the water used in washing clothes has led to the development of the so-called "cold-water" detergents. These detergents are either powders or liquids. The more successful, heavy-duty, liquid detergents generally contain about 30% to about 40 % total surfactants being a combination of non-ionic and anionic types. In addition, such commercially successful, heavy-duty, liquid detergents usually contain a "coupling" solvent, such as ethanol or propylene glycol.
The surfactants employed, besides requiring a high degree of detergency for today's detergent market, must include a number of other important characteristics. For instance, the material must be substantially completely degradable by the action of microorganisms in a relatively short period of time. Also, it is desirable that the heavy-duty, liquid detergent compositions be clear and uniform at room temperature and remain so for relatively long periods of time. In particular, the heavy-duty, liquid detergent compositions should, desirably, remain clear and fluid at temperatures of about 50.degree. F. or even lower (e.g.-less than about 40.degree. F.). In addition, such compositions should return to their original form of clarity and appearance, in the event of such cooling or freezing, simply by standing at room temperature without agitation or mixing. This latter property is referred to as "freeze-thaw stability".
Among the more widely used commercial, non-ionic surfactants are the ethylene oxide adducts of C.sub.12-15 alcohols containing about 60% to 70% ethylene oxide. However, these adducts are from petroleum feed-stocks and have, over the last few years, been subject to significant price increases.
Accordingly, it would be desirable to provide non-ionic surfactants possessing the unique combination of properties which would render such suitable for use in cold-water detergents and which would provide an alternative to the petroleum derived materials.