RHOPLEX® WL-81

Viscosity Control

RHOPLEX® WL-81 polymer is designed so that external thickeners are not required. Many of the glycol ethers on the market today will swell the latex particles, thereby increasing their effective volume and increasing the viscosity. The addition of ammonia or other amines (e.g., dimethylethanolamine) to the swollen particles will further increase viscosity.

Figure 1: Typical pH vs Viscosity Profile

• The degree of swelling by various coalescents is illustrated in Figure II. The effect of the level of coalescent on viscosity response is shown in Figure III. The proper choice and level of coalescents combined with the use of ammonia or organic amine enable the formulator to control the viscosity response.
• Pigmentation will also affect viscosity. Pigments with low-soluble ion concentration (e.g., Snowflake™ calcium carbonate extender) will reduce slightly the viscosity response to ammonia or other amines. Pigments with a higher soluble ion content (e.g., medium chrome and zinc yellow) will have larger effects. In formulating with these pigment types, the viscosity is more readily controlled by using a coalescent concentration/solids approach and depending less on pH response.

Figure 2: Effect of Coalescent Type on Viscosity

Figure 3: Effect of Coalescent Concentration on Viscosity

Based on its composition, RHOPLEX® WL-81 polymer is not expected to be acutely toxic via single oral or dermal exposure. It may be a mild to moderate skin, eye, or respiratory irritant.