Detergents esterquats

Once on the fabric, the quaternaries withstand several rinses in plain water [1,97,98], They are partly removed by anionic surfactants in subsequent washes [6,31], but quat removal is never complete, even after two washes with a detergent [26,96], The situation is probably different with esterquats because of the hydrolysis that takes place under the alkaline conditions of the wash. In fact, only 25% of the DHTDMAC present on the fibers is removed during a wash with SLS, 75% remaining as a catanionic complex [72], Molecules with the longest alkyl chain derivatives best resist cumulative rinses [20],... 

In contrast to alkyl-based cationics, esterquats contain ester groups in the molecule. Owing to this hydrolytically unstable function in the molecule, esterquats are much better biodegradable than alkyl-based cationics. In the European detergent industry, this fact and its lower toxicity to water organisms [21] led to a nearly complete replacement of DSDMAC by esterquats in household rinse cycle softeners since 1991. 

By far the largest use of esterquats today is as actives in rinse cycle softener formulations. Softeners at the same time have the largest single use of quaternary ammonium compounds. The breakthrough of esterquats in this application was in 1991, when European detergent manufacturers reformulated their rinse cycle softeners due to pressure from environmental authorities. The active compound under concern, di(hydrogenated-tallow)dimethylammonium chloride (DHTDMAC), which had been used safely for more than 30 years in fabric softeners, was given an environmentally hazardous classification suddenly. The reason was that there was evidence from laboratory studies that the PEC of DHTDMAC may have exceeded its PNEC, particularly in poorly diluted surface waters. 

The third form of fabric softeners, the softergents, provides detergency and softening during the wash cycle. These formulations contain quaternary ammonium compounds together with nonionic, anionic surfactants and other detergent ingredients. Esterquats can be used in these formulations as well [82-87]. 

Triethanolamine-based esterquats have been found to improve the cold water dispersibility of detergent granules containing fatty alcohol sulfates [93]. 

Monoesterquats based on dimethylethanolamine [94] have been suggested in a number of patent applications for use in granular detergents, in the presence of other additives like anionic, nonionic, or zwitterionic surfactants, enzymes, various soil release polymers, and hydrophobic bleach additives. These compositions showed improved detergency on specific stains [82,95-101]. Esterquat-containing formulations for detergent compositions (powder, liquid, or tablet) are described [102]. 

Alkylolamine-based esterquats hydrophobize clays for their use as viscosity promoters in drilling emulsions [186] and improve the oil wettability of finely divided solids used as fluid loss additive for drilling fluids [187]. Detergent mixtures for tertiary recovery of crude oil contain alkyl oligoglyco-sides and esterquats [188]. Esterquats derived from TEA, MDEA, and DMAPD are claimed for use as collectors in mineral flotation [189]. 

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