Natrosol Plus 330 Hydrophobically modified hydroxyethylcellulose Hercules-Aqualon Rheology Modifier/ Thickener >> Cellulosic, non associative >> Methyl Hydroxyethyl cellulose (MHEC) Coatings >> Waterborne During development of Natrosol® Plus hydrophobically modified hydroxyethylcellulose (HMHEC), it was shown that rheological performance is affected by both nonvolatile volume (NVV) and pigment volume concentration (PVC). Aqualon Booklet 250-18 presents in detail this information, which helps confirm the associative thickening mechanism of Natrosol Plus. Surfactants (wetting agents) are used in most paint formulas to improve the wettability and dispersibility of the pigments, and to improve substrate wettability. Natrosol Plus HMHEC has been shown to interact with surfactants in the aqueous phase of many systems. The question thus arose: How do these surfactants affect the performance of Natrosol Plus? Part of this question was addressed in Booklet 250-18 (in the section entitled Surfactant HLB), where rheological performance vs hydrophilic-lipophilic balance (HLB) of a series of alkylphenol ethoxylate surfactants (the Igepal 1) series) is presented. (See Table 2.) Recall that leveling improves as the HLB decreases, while high-shear viscosity improves as HLB increases. Anionic surfactants were not examined as part of that work, but are included here. The anionic surfactant chosen was Triton 2) GR-7M sodium sulfosuccinate. (Aerosol OT 3) is a comparable product.) The paint was a vinyl-acrylic flat prepared at two PVC and two NVV levels. To simplify the study, titanium dioxide was the only pigment used. (See Tables II and III for formulations.) Figures 1 and 2 show the effect on thickening efficiency 4) of Natrosol Plus when lgepal CO-610, a nonylphenol ethoxylate, is replaced with Triton GR-7M on an equal-actives basis. GR-7M vastly improves the thickening efficiency of Natrosol Plus at both 32 and 63 PVC across the entire NVV range. 1) GAF Corp. 2) Rohm and Haas Company 3) American Cyanamid Company 4) Amount of cellulosic added to a paint to thicken the paint to 100 ± 2 KU Figure 1 – Influence of Pigments and Surfactants on Thickening Efficiency of Natrosol Plus vs Nonvolatile Volume (PVC 63) Natrosol 250 HBR (see Figures 3 and 4) and Natrosol 250 GR were also studied in this work. The data show that Natrosol is unaffected by surfactant choice. Figure 3 – Influence of Pigments and Surfactants on Thickening Efficiency of Natrosol 250 HBR vs Nonvolatile Volume (PVC 63) Figure 4 – Influence of Pigments and Surfactants on Thickening Efficiency of Natrosol 250 HBR vs Nonvolatile Volume (PVC 32) Hydrophobically modified hydroxyethylcellulose (HMHEC). Rheological performance affected by both nonvolatile volume (NVV) and pigment volume concentration (PVC). Interacts with surfactants (wetting agents), can be used in most paint formulas to improve the wettability and dispersibility of the pigments, in the aqueous phase of many systems. Anionic wetting agents are used to improve the thickening efficiency of it. Unaffected by surfactant choice. Leveling improves as the HLB decreases, while high-shear viscosity improves as HLB increases.