Method for preparing biodegradable fabric softening compositions

Claim 1

A method for preparing aqueous biodegradable shelf-stable fabric softening compositions comprising the steps of: (a) combining a C 1 -C 4 monohydric alcohol with a biodegradable quaternary ammonium softening compound of the formula: ##STR19## wherein each R is a C 1 -C 6 alkyl or hydroxyalkyl group, or mixtures thereof; each R' is a C 13 -C 19 hydrocarbyl group, or mixtures thereof; R" is a C 1 -C 4 hydrocarbyl group; and X - is a softener-compatible anion; to form a mixture wherein the amount of the C 1 -C 4 monohydric alcohol comprises from about 5% to about 50% by weight of the biodegradable quaternary ammonium softening compound; (b) heating said mixture to a temperature of from about 60° C. to about 90° C. to form a fluidized melt; (c) diluting said melt with water, heated to a temperature of from about 50° C. to about 85° C., to a concentration of from about 1% to about 25% by weight of the biodegradable quaternary ammonium softening compound to form a dilute mixture; (d) mixing said dilute mixture with a high shear mixer to form a homogeneous mixture with the softener compound having a particle size of from about 0.1 to about 0.5 microns; and (e) adjusting the pH of said homogenous mixture to from about 2.0 to about 5.0 by adding a sufficient amount of a Bronsted acid to the homogeneous mixture to thereby form said fabric softening compositions wherein said compositions are maintained substantially free of free amines.

Claim 2

A method for preparing aqueous biodegradable shelf-stable fabric softening compositions comprising the steps of: (a) combining a C 1 -C 4 monohydric alcohol with a biodegradable quaternary ammonium softening compound of the formula: ##STR19## wherein each R is a C 1 -C 6 alkyl or hydroxyalkyl group, or mixtures thereof; each R' is a C 13 -C 19 hydrocarbyl group, or mixtures thereof; R" is a C 1 -C 4 hydrocarbyl group; and X - is a softener-compatible anion; to form a mixture wherein the amount of the C 1 -C 4 monohydric alcohol comprises from about 5% to about 50% by weight of the biodegradable quaternary ammonium softening compound; (b) heating said mixture to a temperature of from about 60° C. to about 90° C. to form a fluidized melt; (c) diluting said melt with water, heated to a temperature of from about 50° C. to about 85° C., to a concentration of from about 1% to about 25% by weight of the biodegradable quaternary ammonium softening compound to form a dilute mixture; (d) mixing said dilute mixture with a high shear mixer to form a homogeneous mixture with the softener compound having a particle size of from about 0.1 to about 0.5 microns; and (e) adjusting the pH of said homogenous mixture to from about 2.0 to about 5.0 by adding a sufficient amount of a Bronsted acid to the homogeneous mixture to thereby form said fabric softening compositions wherein said compositions are maintained substantially free of free amines.