Associative thickener

Alkali-soluble emulsion that improves the high-shear viscosity of a formulation. Recommended in conjunction with the ACRYSOL ASE thickeners to maintain viscosity at high shear rates. Not recommended as a primary thickener in most applications. 

Acrylic emulsion copolymer with same advantages and applications as ACRYSOL TT-615 but not as efficient at low shear rates. Is less shear thinning and imparts a leggier rheology. 

ROHM AND HAAS CO. ACRYSOL Thickeners and Rheology Modifiers (Continued)  

Efficient thickener that imparts more Newtonian rheology. Provides excellent holdout when coating fabric such as rainwear. 

Same advantages and applications as RHEOLOGY MODIFIER QR-708 but supplied at a lower viscosity for easier handling and formulating. 

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Chain-Growth Associative Thickeners. Preparation of hydrophobically modified, water-soluble polymer in aqueous media by a chain-growth mechanism presents a unique challenge in that the hydrophobically modified monomers are surface active and form micelles (50). Although the initiation and propagation occurs primarily in the aqueous phase, when the propagating radical enters the micelle the hydrophobically modified monomers then polymerize in blocks. In addition, the hydrophobically modified monomer possesses a different reactivity ratio (42) than the unmodified monomer, and the composition of the polymer chain therefore varies considerably with conversion (57). The most extensively studied monomer of this class has been acrylamide, but there have been others such as the modification of PVAlc. Pyridine (58) was one of the first chain-growth polymers to be hydrophobically modified. This modification is a post-polymerization alkylation reaction and produces a random distribution of hydrophobic units. 

HydrophobicaHy Modified, Ethoxylated Urethane. HEUR associative thickeners are in effect poly(oxyethylene) polymers that contain terminal hydrophobe units (66). They can be synthesized via esterification with monoacids, tosylation reactions, or direct reaction with monoisocyanates. There are problems associated with aH of the methods of synthesis. The general commercial procedure for their synthesis is by a step-growth addition of... 

Resin Solubilizers. In general, water-soluble resins ate amine salts of acidic polymers. Water-soluble coatings formulated with AMP-95 and DMAMP-80 exhibit superior performance (15,16) (see Water-SOLUBLE polymers). AMP-95, used in conjunction with associative thickeners (17) or hydroxy-ethylceUulose, provides for the most efficient utilization of such thickeners. It also is the neutralizer of choice for use with hair spray resins. 

The level of technical service support provided for a given product generally tracks in large part where the suppHer considers thek product to be located within the spectmm of commodity to specialty chemicals. Technical service support levels for pure chemicals usually provided in large quantities for specific synthetic or processing needs, eg, ammonia (qv), sulfuric acid (see SuLFURic ACID AND SULFURTRIOXIDe), formaldehyde (qv), oxygen (qv), and so forth, are considerably less than for more complex materials or blends of materials provided for multistep downstream processes. Examples of the latter are many polymers, colorants, flocculants, impact modifiers, associative thickeners, etc. For the former materials, providing specifications of purity and physical properties often comprises the full extent of technical service requked or expected by customers. These materials are termed undifferentiated chemicals (9),... 

The specific nature of the interactions among hydrophobes would suggest that the associative thickeners will vary in performance with the different latices and components used in coatings formulations. This has been observed(29) in... 

Glass, J.E., ed. "The Influence of Associative Thickeners and Rheology on Coatings Performance," 1983, Fargo, N.D. North Dakota State University Press. 

Hydrophobe-modification of hydroxyethylcellulose produces w hat should be considered model associative thickeners, for the distribution of hydroxycthyl units has been characterized. The commercial material, a Hercules product, contains three hydrophobes per chain. 

HEUR associative thickeners are in effect poly(oxyethylene) polymers that contain terminal hydrophobe units. They can be synthesized via esterification with monoacids. tosylation reactions, or direct reaction with monoisocyanates. 

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