Dispersants & Scale Inhibitors

Cooling tower

Aquero Company offers polyaspartates and copolymers of aspartate and other residues, particularly asparagine and succinimide.  These molecules are available in linear or branched forms and span the Mw range from oligomers (Mw 500 to 1000) to Mw's 100,000 and higher.  These polyaspartates are unique, proprietary, and are being evaluated by other companies for a variety of uses.

The story of polyaspartates through the 1980's and 90's is mainly about dispersants and antiscalants.  The main commercial uses of polyaspartate at present are as dispersants and antiscalants in oilfield uses and in detergents.  The oilfield application began in the North Sea fields, driven by environmental regulations.  It is also used in oilfields elsewhere to a limited extent.  Being "green", polyaspartate found a use in environmentally friendly detergents.  This has also been a comparatively small market.

As a polyanion, polyaspartate acts as an inhibitor of inorganic crystal growth such as occurs during scaling of heat-exchange surfaces in cooling towers, boilers, and other process equipment.  Mineral deposition also occurs, for example, during the rinse and drying cycles of cleaning of cloth and dishware.   Polyanions also act to disperse mineral particulates, keeping them from aggregating or forming a film.  Particularly if nascent crystallites and soil particles aren't dispersed during the wash, they may deposit on the fibers and or glass and dish surfaces.  The fibers don't end up feeling soft and the surfaces in general may look hazy or dingy.

Before 1980, the main additives for antiscaling applications were the phosphonates.  These are small molecules, but very effective.  They still are in widespread use.  Through the 1980's and continuing to the present, the polyacrylates and related vinyl polymers enjoyed growing markets in both antiscaling and dispersancy, eventually dominating and remaining dominant today.

The polyaspartates perform well in both of these applications, but most polyaspartates do not compete so well on cost.  The polyaspartate made via a maleic acid plus ammonia approach to thermal polycondensation is the low-cost polyaspartate and is cost-competitive.  However, the Mw of this form is low at around 3,000 and the synthetic route leads to branching.  This limits the effectiveness of this polyaspartate in a number of applications.

The polyaspartate made via thermal polycondensation of aspartic acid has a somewhat higher Mw in the range of 5,000 and has a more linear morphology.  It performs better in some applications, but again has limited utility in others.  Plus it doesn't compete as well on cost.

Aquero Company provides samples of its novel polyaspartates to interested parties on a collaborative basis.