EcoSphere® forms stable mixed emulsions when blended with synthetic latexes. These blends benefit from the self-lubricating nature of EcoSphere. EcoSphere and its blends exhibit improved water holding properties. This eliminates the need for rheology modifiers (thickeners) in most coating color formulations.

In contrast to the hard colloidal properties of synthetic latexes, EcoSphere can be described as a “squishy” colloid. Its shape deforms under high shear conditions. This improves runnability, permitting high solids blade stability and promotes reduced misting. Users of pond size presses have noticed decreased pond turbulence and runnability that rivals the best ever seen on their equipment.

Many coating color recipes use insolubilizers when industrial cooked starch is used in the formula. EcoSphere will compete with the cooked starch for the insolubilizer meaning that an optimization of components may be necessary for peak paper and print performance.

There are a number of different insolubilizer technologies, including glyoxal based systems, zirconium carbonate systems and amine based systems. Generally, they are selected based on the type of synthetic latex used. Selection depends on the surface modification of the synthetic latex. Glyoxal based systems usually are designed to react best with the hydroxyl functionality of starch, while zirconium carbonate systems are preferred and designed to react with the carboxyl functionality of SB and SA Latex binders. While both amine and zirconium carbonate based insolubilizers work with EcoSphere, glyoxal based systems bring out the best performance characteristics. Control of the pH of coating color formulations is important in order to avoid premature crosslinking reactions of the insolubilizer with EcoSphere biolatex particles. This typically occurs below a pH of 7.5. While the impact may go unnoticed with a minor portion of a low molecular weight soluble cooked starch, such premature reactions can have a significant impact on both low and high shear viscosity for EcoSphere. The optimum pH after insolubilizer addition is 8.0 to 8.5. Given that most glyoxal based systems are acidic, the pH is typically adjusted to 8.5 to 9.0 prior to their addition. The pH should be adjusted with dilute base, as concentrated base could affect the performance and viscosity of EcoSphere.

EcoSynthetix recommends optimization of the type of insolubilizer and order of addition of EcoSphere into the formulation to ensure peak paper performance.

EcoSphere can be dispersed at ambient temperature directly into the coating color, or it can be pre-dispersed. Care should be taken to keep the coating color formulation below 60°C if the final dispersion is to be stored for several hours. This prevents the formation of color and controls the crosslinking reaction to maintain acceptable application viscosity. See the Mixing Guide for details.

Some paper mills use a defoamer to control foam formation. Many of these defoamers are oil based. They are often stabilized by surfactant and at times depend on the surfactant used to stabilize the synthetic latex emulsion. When the synthetic latex percentage of the coating formula is reduced, the level of surfactant in the formula decreases by the same percentage. As this surfactant presence decreases, it results in decreasing compatibility of the formulation. This can impact gloss (due to surface imperfections), result in gels, fisheyes, and other surface phenomena, and it can lead to reduced brightness. If this problem occurs, the simplest solution is to reduce or eliminate the defoamer. Alternatively, a small amount of compatible surfactant is added.

EcoSphere is internally plasticized by the water that it retains. This permits a more pliable surface and improved gloss under mild calendering conditions. While strong calendering (increased heat/pressure) benefits gloss formation in synthetic latexes, it does not promote optimum gloss formation in EcoSphere. Drying conditions can also impact paper characteristics. While synthetic latexes are often hit fast and hard with high heat to ensure immobilization, coalescence, minimize mottle and surface stickiness and maximize gloss, maximum gloss with EcoSphere is generally achieved with milder drying conditions.

It is also important to ensure that the ultimate % moisture of the paper or paperboard product is 5-6%, and certainly not less than 3%, in order to ensure the EcoSphere biolatex binder remains flexible for calendering.

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