Quaternary fatty diesters of hydroxypropyl diethanol amine

#Fatty diester quaternary salts have been used in fabric softeners for a few years now. Their advantage over other fatty quaternary salts is that they exhibit rapid biodegradability relative to conventional fabric softening agents be they fatty alkyl or fatty alkyl amido types. However, even though fatty ester quaternary salts have been shown to be more biodegradable than their fatty alkyl or fatty alkylamido analogues, they are also more difficult to formulate, including previously patented triethanolamine fatty ester quaternary salts. A fatty ester quaternary salt exhibiting a lower handling temperature enabling it to be stored at lower temperatures and transferred from one vessel to another with greater ease would also be desired.

#These needs are met by the present invention. In accordance with one embodiment of the present invention, there is provided a quaternary fatty diester of 2-hydroxypropyl diethanol amine having the structure of Formula I: ##STR1## wherein each R is independently selected from aliphatic hydrocarbon groups having from about 8 to about 24 carbon atoms; R.sub.1 is independently selected from hydrogen, benzyl groups and one to four carbon atom alkyl groups; and X is an anion.

#The present invention provides fatty diester quaternary salts that are water dispersible yet confer an exceptional hand feel to fabrics treated therewith that has long been desired for use in laundering and in personal care products. Therefore, in accordance with another embodiment of the present invention, aqueous dispersions of the fatty diester quaternary salts of the present invention are provided, which may be additionally formulated with conventional laundering and personal skin and hair care active ingredients.

#The fabric softening agents of the present invention are quaternary salts of fatty diesters of hydroxypropyl diethanol amine. Fatty acids suitable for use in the present invention may contain from 8 to 24, and preferably from 16 to 18, carbon atoms. The fatty acids may be saturated, unsaturated or polyunsaturated, Hydroxyl-substituted castor oil-type fatty acids may also be employed. The fatty acids may also be branched. Iso-branched fatty acids are particularly desirable because they impart liquidity to the compounds of the present invention.

#Examples of such fatty acids include caprylic, capric, decanoic, undecanoic, lauric, dodecanoic, tridecanoic, myristic, tetradecanoic, pentadecanoic, hexadecanoic, palmitic, heptadecanoic, stearic, oleic, linoleic, linolenic, nonadecanoic, eicosanoic, behenic, tetracosanoic and the like. The preferred fatty acids or the mixtures thereof may be derived from tallow, soy bean, rape seed or coconut oil. Tall oil fatty acids are also exemplary of a naturally occurring mixture of acids suitable for use in the present invention.

#For purposes of the present invention "fatty acids" are defined as including, in addition to the fatty acid itself, the alkyl esters thereof and the naturally occurring glyceride esters. In the methods of the present invention, the glyceride ester form of the fatty acid splits in the course of the initial condensation of the fatty acid moiety and the hydroxypropyl diethanol amine, and the glycerol by-product can be readily removed from the reaction mixture by conventional means. Because the naturally occurring glyceride form of the above-listed animal and vegetable derived fatty acids are more economical than the free acids or the monoesters, it is particularly preferred to use these fatty acids in this form.