Guidelines for UCAR POLYPHOBE Rheology Modifiers

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Latexes
UCAR™ POLYPHOBE™ Rheology Modifiers are most efficient with small particle size, hydrophobic latexes, such as all-acrylics or styrene acrylics. Thickener efficiency increases with increased paint volume solids and decreased PVC.

Dispersants
Dispersant choice can have a dramatic impact on thickener efficiency, viscosity stability, gloss, scrub resistance, and colorant development. Dispersant selection should be made in accordance with the latex binder type and coating pigmentation. Generally, the use of hydrophilic copolymer dispersants such as "Tamol" 1124 or "Rhodaline" 286N will result in optimum stability, gloss and water resistance in vinyl acrylic systems. Hydrophobic copolymers may also be employed in these systems when used in conjunction with KTPP or other hydrophilic dispersants. Examples of hydrophobic dispersants are "Tamol" 731 or "Rhodaline" 111.

Hydrophobic dispersants such as "Tamol" 731, "Tamol" 165 or "Rhodaline" 111M will result in better system compatibility with more hydrophobic latexes such as all-acrylics or styrene acrylics. When appropriate, the use of a portion of the UCAR POLYPHOBE thickener in the grind may enhance gloss, hiding and grind efficiency.

Coalescing Solvents
Due to the film-forming nature of the UCAR POLYPHOBE thickeners, they should be considered when determining the coalescing solvent demand. Typically, higher levels of coalescent are required in formulations when employing HASE thickeners than when utilizing HEUR or HEC.

A coalescent ladder should be performed early in the formulation development to ensure complete film formation.

Increased levels of hydrophobic filming aids such as UCAR Filmer IBT or "Texanol" tend to increase thickener efficiency but may also impact gloss, leveling, ICI viscosity, and surface wetting. Hydrophilic cosolvents such as Butyl CARBITOL™ Solvent have the greatest effect on reducing thickener efficiency.

Early wet adhesion to glossy alkyd substrates (dry time <24 hours) may be negatively affected by higher levels of coalescing solvents.

Ethylene and propylene glycol appear to have minor effects on the rheology developed by UCAR POLYPHOBE thickeners.

Neutralizing Agents
Use "AMP-95" in interior formulations for improved stability and gloss. In exterior applications, ammonium hydroxide is the preferred neutralizing base due to its rapid volatilization from the film, ensuring rapid development of maximum water-resistant property of the film.

Pigments
Certain extender pigments such as hydrophobic clays have been found to improve thickener efficiency.

Incorporation Options
When a portion of UCAR POLYPHOBE Rheology Modifier is placed in the grind, it can function as a partial dispersant. The preferred order of addition in the grind is as follows: water, dispersants/wetting agents, pigments, defoamers, UCAR POLYPHOBE Rheology Modifier, and neutralizing base to adjust pH to 8-10.

When a UCAR POLYPHOBE thickener is placed in the letdown, neutralizing base can be added either before or after the addition of the thickener. Adding the base first helps maintain stability of the pigment and latex dispersions. When using this order of addition, it is highly recommended that the UCAR POLYPHOBE thickener be diluted 1:1 with water to avoid formation of thickener gel particles.

Adding the neutralizing base last is advantageous because it minimizes thickener gel particles and provides for the most rapid thickener incorporation and equilibration.

Miscellaneous
Interior paints formulated with UCAR POLYPHOBE thickeners usually exhibit superior blocking resistance versus those formulated with HEUR thickeners. In exterior paints this improved block resistance results in reduced dirt pickup, which can further lead to improved mildew resistance.

The filming properties of UCAR POLYPHOBE thickeners versus HEUR thickeners or HEC generally result in improved stain removal properties and efflorescence resistance.