Alkylbenzenesulfonate surfactants

Details Alkylbenzenesulfonate surfactants Alkylbenzenesulfonate surfactants

2000-01-07

2001-10-23

Ogden, Necholus (Department: 1751)

Cleaning compositions for solid surfaces, auxiliary compositions

Auxiliary compositions for cleaning, or processes of preparing

Surfactant composition for cleaning agents

C510S357000, C510S424000, C510S426000, C510S428000

Reexamination Certificate

active

06306817

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to improved detergent and cleaning products containing particular types of alkylarylsulfonate surfactants. More particularly, these alkylarylsulfonates have chemical compositions which differ both from the highly branched nonbiodegradable or “hard” alkylbenzenesulfonates still commercially available in certain countries; and which differ also from the so-called linear alkylbenzenesulfonates which have replaced them in most geographies, including the most recently introduced so-called “high 2-phenyl” types. Moreover the selected surfactants are formulated into new detergent compositions by combination with particular detergent adjuncts. The compositions are useful for cleaning a wide variety of substrates.
BACKGROUND OF THE INVENTION
Historically, highly branched alkylbenzenesulfonate surfactants, such as those based on tetrapropylene (known as “ABS”) were used in detergents. However, these were found to be very poorly biodegradable. A long period followed of improving manufacturing processes for alkylbenzenesulfonates, making them as linear as practically possible (“LAS”). The overwhelming part of a large art of linear alkylbenzenesulfonate surfactant manufacture is directed to this objective. All relevant large-scale commercial alkylbenzenesulfonate processes in use today are directed to linear alkylbenzenesulfonates. However, linear alkylbenzenesulfonates are not without limitations; for example, they would be more desirable if improved for hard water and/or cold water cleaning properties. Thus, 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 alkylbenzenesulfonates, 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 alkylbenzenesulfonate.
Accordingly it would be very desirable to simplify detergent formulations and deliver both better performance and better value to the consumer. Moreover, in view of the very large tonnages of alkylbenzenesulfonate surfactants and detergent formulations used worldwide, even modest improvements in performance of the basic alkylbenzenesulfonate detergent could carry great weight.
To understand the art of making and use of sulfonated alkylaromatic detergents, one should appreciate that it has gone through many stages and includes (a) the early manufacture of highly branched nonbiodegradable LAS (ABS); (b) the development of processes such as HF or AlCl
3
catalyzed process (note each process gives a different composition, e.g., HF/olefin giving lower 2-phenyl or classic AlCl
3
/chloroparaffin typically giving byproducts which though perhaps useful for solubility are undesirable for biodegradation); (c) the market switch to LAS in which a very high proportion of the alkyl is linear; (d) improvements, including so-called ‘high 2-phenyl’ or DETAL processes (in fact not really “high” 2-phenyl owing to problems of solubility when the hydrophobe is too linear); and (e) recent improvements in the understanding of biodegradation.
The art of alkylbenzenesulfonate detergents is extraordinarily replete with references which teach both for and against almost every aspect of these compositions. For example, some of the art teaches toward high 2-phenyl LAS as desirable, while other art teaches in exactly the opposite direction. There are, moreover, many erroneous teachings and technical misconceptions about the mechanism of LAS operation under in-use conditions, particularly in the area of hardness tolerance. The large volume of such references debases the art as a whole and makes it difficult to select the useful teachings from the useless without large amounts of 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. According to the literature, and general practice, surfactants having alkali or alkaline earth salts that are relatively insoluble (their Na or Ca salts have relatively high Krafft temperature) are less desirable than those having alkali or alkaline earth salts which are relatively higher in solubility (Na or Ca salts have lower Krafft temperature). In the literature, LAS mixtures in the presence of free Ca or Mg hardness are said to precipitate. It is also known that the 2- or 3-phenyl or “terminal” isomers of LAS have higher Krafft temperatures than, say, 5- or 6-phenyl “internal” isomers. Therefore, it would be expected that changing an LAS composition to increase the 2- and 3-phenyl isomer content would decrease the hardness tolerance and solubility: not a good thing. On the other hand it is also known that with built conditions under which both the 2- and 3-phenyl and internal-phenyl isomers at equal chain length can be soluble, the 2- and 3-phenyl isomers are more surface-active materials. Therefore, it would be expected that changing an LAS composition to increase the 2- and 3-phenyl isomer content may increase the cleaning performance. However, the unsolved problems with solubility, hardness tolerance, and low temperature performance still remain.
BACKGROUND ART
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. 5,087,788; 5,625,105 and 4,973,788 are useful by way of background to the invention. The manufacture of alkylbenzenesulfonate 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. Documents referenced herein are incorporated in their entirety.
SUMMARY OF THE INVENTION
It is an aspect herein to provide improved detergent compositions comprising certain sulfonated alkylbenzenes. It is another aspect to provide the improved surfactants and surfactant mixtures comprising the same. These and other aspects of the present invention will be apparent from the description hereinafter.
The present invention has numerous advantages beyond satisfying one or more of the aspects identified hereinabove, including but not limited to: superior cold-water solubility, for example for cold water laundering; superior hardness tolerance; and excellent detergency, especially under low-temperature wash conditions. Further, the invention is expected to provide reduced build-up of old fabric softener residues from fabrics being laundered, and improved removal of lipid or greasy soils from fabrics. Benefits are expected also in non-laundry cleaning applications, such as dish cleaning. The development offers substantial expected improvements in ease of manufacture of relatively high 2-phenyl sulfonate compositions, improvements also in the ease of making and quality of the resulting detergent formulations; and attractive economic advantages.
The present invention is based on an unexpected discovery that there exist, in the middle ground between the old, highly branched, nonbiodegradable alkylbenzenesulfonates and the new linear types, certain alkylbenzenesulfonates which are both more highly performing than the latter and more biodegradable than the former.
The new alkylbenzenesulfonates are read

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