Laundry detergents comprising modified alkylbenzene sulfonates

Details Laundry detergents comprising modified alkylbenzene sulfonates Laundry detergents comprising modified alkylbenzene sulfonates

2001-04-12

2003-06-24

Ogden, Necholus (Department: 1751)

Cleaning compositions for solid surfaces, auxiliary compositions

Cleaning compositions or processes of preparing

For cleaning a specific substrate or removing a specific...

C510S424000, C510S426000, C510S428000, C510S492000

Reexamination Certificate

active

06583096

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to particular types of alkylbenzene sulfonate surfactant mixtures containing branching and adapted for laundry and cleaning product use by controlling compositional parameters, especially a 2/3-phenyl index and a 2-methyl-2-phenyl index, as well as to improved detergent and cleaning products containing these surfactant mixtures, to alkylbenzene precursors for the surfactant mixtures, and to methods of making the precursors as well as the surfactant mixtures. The present compositions are especially useful for fabric laundering.
BACKGROUND OF THE INVENTION
Historically, highly branched alkylbenzene sulfonate surfactants, such as those based on tetrapropylene, known as “ABS” or “TPBS”, were used in detergents. However, these were found to be very poorly biodegradable. A long period followed of improving manufacturing processes for alkylbenzene sulfonates, making them as linear as practically possible, hence the acronym “LAS”. The overwhelming part of a large art of linear alkylbenzene sulfonate surfactant manufacture is directed to this objective. All relevant large-scale commercial alkylbenzene sulfonate processes in use today are directed to linear alkylbenzene sulfonates. However, linear alkylbenzene sulfonates are not without limitations, for example, they would be more desirable if improved for hard water cleaning and/or cold water cleaning properties. They can often fail to produce good cleaning results, for example when formulated with nonphosphate builders and/or when used in hard water areas.
As a result of the limitations of the alkylbenzene sulfonates, consumer cleaning formulations have often needed to include a higher level of cosurfactants, builders, and other additives than would have been needed given a superior alkylbenzene sulfonate.
The art of alkylbenzene sulfonate detergents is replete with references which teach both for and against almost every aspect of these compositions. Moreover, there are believed to be erroneous teachings and technical misconceptions about the mechanism of LAS operation under in-use conditions, particularly in the area of hardness tolerance. The volume of such references debases the art as a whole and makes it difficult to select the useful teachings from the useless without repeated experimentation. To further understand the state of the art, it should be appreciated that there has been not only a lack of clarity on which way to go to fix the unresolved problems of linear LAS, but also a range of misconceptions, not only in the understanding of biodegradation but also in basic mechanisms of operation of LAS in presence of hardness.
Also, while the currently commercial, essentially linear alkylbenzene sulfonate surfactants are relatively simple compositions to define and analyze, compositions containing both branched and linear alkylbenzene sulfonate surfactants are complex. In general such compositions can be highly varied, containing one or more different kinds of branching in any of a number of positions on the aliphatic chain. A very large number, e.g., hundreds, of distinct chemical species are possible in such mixtures. Accordingly there is an onerous burden of experimentation if it is desired to improve such compositions so that they can clean fabrics better in detergent compositions while at the same time remaining biodegradable. The formulator's knowledge is key to guiding this effort.
Yet another currently unresolved problem in alkylbenzene sulfonate manufacture is to make more effective use of current LAB feedstocks. It would be highly desirable, both from a performance point of view and from an economic point of view, to better utilize certain desirable types of branched hydrocarbons.
Accordingly there is a substantial unmet need for further improvements in alkylbenzene sulfonate surfactant mixtures, especially with respect to those offering one or more of the advantages of superior cleaning, hardness tolerance, satisfactory biodegradability, and cost.
BACKGROUND ART
U.S. Pat. Nos. 5,659,099, 5,393,718, 5,256,392, 5,227,558, 5,139,759, 5,164,169, 5,116,794, 4,840,929, 5,744,673, 5,522,984, 5,811,623, 5,777,187, WO 9,729,064, WO 9,747573, WO 9,729,063, U.S. Pat. Nos. 5,026,933; 4,990,718; 4,301,316; 4,301,317; 4,855,527; 4,870,038; 2,477,382; EP 466,558, Jan. 15, 1992; EP 469,940, Feb. 5, 1992; FR 2,697,246, Apr. 29, 1994; SU 793,972, Jan. 7, 1981; U.S. Pat. Nos. 2,564,072; 3,196,174; 3,238,249; 3,355,484; 3,442,964; 3,492,364; 4,959,491; WO 88/07030, Sep. 25, 1990; U.S. Pat. Nos. 4,962,256, 5,196,624; 5,196,625; EP 364,012 B, Feb. 15, 1990; U.S. Pat. Nos. 3,312,745; 3,341,614; 3,442,965; 3,674,885; 4,447,664; 4,533,651; 4,587,374; 4,996,386; 5,210,060; 5,510,306; WO 95/17961, Jul. 6, 1995; WO 95/18084; U.S. Pat. Nos. 5,510,306; 5,087,788; 4,301,316; 4,301,317; 4,855,527; 4,870,038; 5,026,933; 5,625,105 and 4,973,788. The manufacture of alkylbenzene sulfonate surfactants has recently been reviewed. See Vol 56 in “Surfactant Science” series, Marcel Dekker, New York, 1996, including in particular Chapter 2 entitled “Alkylarylsulfonates: History, Manufacture, Analysis and Environmental Properties”, pages 39-108 which includes 297 literature references. Surfactant-related analytical methods are described in “Surfactant Science” series, Vol 73, Marcel Dekker, New York, 1998 and “Surfactant Science” series, Vol 40, Marcel Dekker, New York, 1992. Documents referenced herein are incorporated in their entirety. See also copending U.S. Patent applications No. 60/053,319 filed on Jul. 21st, 1997, No. 60/053,318, filed on Jul. 21st, 1997, No. 60/053,321, filed on Jul. 21st, 1997, No. 60/053,209, filed on Jul. 21st, 1997, No. 60/053,328, filed on Jul. 21st, 1997, No. 60/053,186, filed on Jul. 21st, 1997 and the art cited therein.
SUMMARY OF THE INVENTION
It has now surprisingly been found that there exist certain alkylbenzene sulfonate surfactant mixtures, hereinafter “modified alkylbenzene sulfonate surfactant mixtures” which offer one or more, and even several of the above-outlined advantages. The discovery of these mixtures solves important problems of the kind described in the background.
Thus in accordance with a first embodiment of the present invention, a novel modified alkylbenzene sulfonate surfactant mixture is provided. This novel surfactant mixture comprises, preferably consists essentially of:
(a) from about 15% to about 99%, preferably from about 15% to about 60%, more preferably from about 20% to about 40%, by weight of a mixture of branched alkylbenzene sulfonates having formula (I):
wherein L is an acyclic aliphatic moiety consisting of carbon and hydrogen, the L having two methyl termini and the L having no substituents other than A, R
1
and R
2
; and wherein the mixture of branched alkylbenzene sulfonates contains two or more, preferably at least three, optionally more of the branched alkylbenzene sulfonates differing in molecular weight of the anion of the formula (I) and wherein the mixture of branched alkylbenzene sulfonates has a sum of carbon atoms in R
1
, L and R
2
of from 9 to 15, preferably from 10 to 14; an average aliphatic carbon content, i.e., based on R
1
, L and R
2
and excluding A, of from about 10.0 to about 14.0, preferably from about 11.0 to about 13.0, more preferably from about 11.5 to about 12.5, carbon atoms; M is a cation or cation mixture, preferably selected from H, Na, K, Ca, Mg and mixtures thereof, more preferably selected from H, Na, K and mixtures thereof, more preferably still, selected from H, Na, and mixtures thereof having a valence q, typically from 1 to 2, preferably 1; a and b are integers selected such that the branched alkylbenzene sulfonates are electroneutral, a is typically from 1 to 2, preferably 1, b is 1; R
1
is C
1
-C
3
alkyl, preferably C
1
-C
2
alkyl, more preferably methyl; R
2
is selected from H and C
1
-C
3
alkyl, preferably H and C
1
-C
2
alkyl, more preferably H and methyl, more preferably H and methyl provided that in at least about 0.5, more preferably 0.7, more preferably 0.9 to 1.0 mole fracti

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