Softeners are added to the laundry in the last rinse cycle of the machine wash to suppress the “dry stiffness” effect that occurs in drying laundry. Dry stiffness originates in the formation of hydrogen bridge bonds between the cellulose fibers. The cationic, softening compounds of the softener penetrate into the fibers or lie on the surface of the fibers, combine with the negative charges and thus weaken the interactions. The reduced stiffness of the laundry item reduces the effort involved in ironing and increases wear comfort.
Liquid softeners are divided into two types: “regular” softeners containing 1 to 5 wt. % of softening compounds and “concentrated” softeners containing 5 to 80 wt. % of softening compounds.
The acceptance of a softener product by users is determined not only by the actual performance but also to a great extent by the viscosity of the product, with medium to high viscosities being preferred by users. Desired viscosities are in the range from 10 to 400 mPas for regular softeners and in the range from 100 to 600 mPas for concentrated softeners (determined in each case with an RV DV II+P Brookfield viscometer; spindle 2 at 20 rpm and 20° C.).
In regular softeners in particular the viscosity after production is often too low, and thickeners are added to the products to increase the viscosity. For example, the use of homopolymers and/or copolymers as thickeners in softeners is known from WO 2004/050812 A1.
The thickeners that are used often have no softening capacity themselves and they increase the manufacturing costs for the softeners. Furthermore, not all thickeners are compatible with the ingredients used in the softeners.
A problem addressed by this invention was therefore to provide a liquid fabric softener composition having a sufficiently high viscosity and containing little or no thickener.
Surprisingly this problem was solved by means of a liquid fabric softener composition containing 0.5 to 40 wt. %, relative to the total fabric softener composition, of a softening mixture of trialkanolamine-based ester quat and trialkanolamine-based ester, the liquid fabric softener composition being free from methanol.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.