Traditional starch occurs in nature in various plant forms including corn, wheat, potato, tapioca and rice.  It consists of microscopic granules used for energy storage by the plant.  Starch requires water, heat and caustic chemicals to dissolve in water.  Because starch is a very large polymer molecule, resultant starch solutions have high viscosity at low solids levels, a property which limits their use in industrial applications.  EcoSynthetix Inc. has developed a patented process that completely removes the native granular structure and reduces the average particle size diameter from 30 microns (= 0.3 mm) to approximately 0.1 micron (= 0.0001 mm) or 100 nanometers (see figure below).

Bottom Up Emulsion Polymerization Process for Petroleum Latex Compared to Top Down Reactive Extrusion Process for Biolatex

Micrographs obtained by Scanning Electron Microscopy (SEM), Environmental SEM (ESEM), and Scanning Transmission Electron Microscopy (STEM)

The Company’s proprietary biopolymer nanoparticle technology represents a technology breakthrough that has led to the world’s first waterborne biopolymer latex.  The fundamental design of the biolatex is similar to that of synthetic latexes, although the process for producing them is completely different.  While synthetic latex is produced by polymerization of petroleum-based monomers in an aqueous emulsion polymerization process (“Bottom Up Approach”), EcoSphere® biolatex is produced from relatively large starch particles (micrograph “a” above) via a “Top Down Approach” using a highly efficient reactive extrusion process.  This process is proprietary to EcoSynthetix.  The process converts starch into an agglomerate of dry crosslinked biopolymer nanoparticles (micrograph “b” above).  The dry agglomerate product can be shipped directly to the customer, where it is readily dispersed in water to form the EcoSphere® biolatex dispersion.  Micrograph “c” above, for a freeze-dried biolatex sample, illustrates the nano-particular form of the biolatex.  This therefore eliminates the cost of shipping water.  SB Latex cannot be shipped dry, but is shipped as a 50% solids dispersion.  Thus, half of the petroleum-based latex weight adds no value to the customer.

The EcoSynthetix proprietary process imparts unique properties to EcoSphere® biolatex that have not been previously observed in industrial starches or petroleum-based binder products.  EcoSphere® is unique because its discrete particles are insoluble and thus form an aqueous polymer colloid (synonyms are water-based latex and emulsion polymer). Like their synthetic analogues, EcoSphere® containing coating formulations can reach high solids levels of up to about 70%.  This is impossible for industrial starches, because they must be dissolved by cooking them to a maximum solids of 25 to 30%.  The end result is that EcoSphere® behaves more like a synthetic latex, not a starch solution.  This opens up new markets and opportunities for EcoSphere® to compete in several areas that were closed to traditional starch co-binders.

Illustration of the Drying Process of Biopolymer Nanoparticles

Petroleum-based binders such as SB Latex are not subject to shrinkage upon drying, and are known to deliver good optical properties including gloss.  EcoSphere® biolatex binders can be used in premium paper grades because they perform favorably when compared to SB Latex binders.  Successful pilot plant and mill trials have shown that EcoSphere® biolatex products do not exhibit conventional starch like qualities.  This is because the crosslinked starch nanoparticles that make up the EcoSphere® biolatex maintain their swollen or expanded structures upon drying (see illustration above), while soluble starches are notorious for shrinkage upon drying.  The shrinkage leads to rough paper coating surfaces and poor optical properties such as gloss.  This is one of the reasons why the use of conventional soluble starches is severely restricted in premium grade papers.  The strength of the crosslinked polymer chains in the biolatex allows for replacement of SB Latex in paper grades where traditional starch cannot be used.  While starch is known to have only half the binding strength of SB Latex, EcoSphere® biolatex has been demonstrated to successfully substitute SB Latex on a one-to-one basis.

When dry EcoSphere® is dispersed in water, it exhibits new desirable properties not previously achievable with starch.  These properties include rapid drying time and stable colloidal behavior (the dispersion does not gel, retrograde or come out of solution).  The stability of EcoSphere® dispersions eliminates the costs and consistency problems associated with “starch cooking” in the coating kitchen of paper and paperboard manufacturing.