Alkali-swellable emulsions

Hydrophobically Modified Alkali-Swellable Emulsions. The hydrophobe modification of acryHc acid represents an important class of... 

The subject of surfactant-modified, water-soluble polymers, briefly discussed in Water-Soluble Polymers, is addressed in the last three sections (Chapters 16-28) of this book. These associative thickeners are covered in detail, ranging from the maleic acid copolymers of variable compositions introduced in various commercial markets in the early 1960s to the most recent entries (that is, in the open literature), hydrophobe-modified poly (acrylamide). Chapter 23 is complementary to the spectroscopic studies in Chapters 13-15 it explores new approaches to understanding associations in aqueous media. The three hydrophobe-modified polymers that have gained commercial acceptance in the 1980s, (hydroxyethyl)cellulose, eth-oxylate urethanes, and alkali-swellable emulsions, are discussed in detail. In particular, hydrophobe-modified (hydroxyethyl)cellulose, which is... 

The two associative thickeners examined in the remainder of this text whose synthesis has not been discussed are hydrophobe-modified alkali-swellable emulsions (HASE) discussed in Chapters 25, 27, and 28, and hydrophobe-modified (hydroxyethyl)cellulose (HMHEC, discussed in Chapters 17, 18, and 27). HASE thickeners, by far the lowest cost hydrophobe-modified thickeners produced, should have achieved the largest market share on the basis of cost of production, but this situation does not appear to be the case (discussed in Chapter 28) in large part because of the poor properties observed with the lowest cost latex, vinyl acetate, used to form the continuous film. The applied-film properties 46) of vinyl acetate can be substantially improved through the use of HEUR polymers. HMHEC, synthesized by a matured (30-year-old) commercial slurry process (47) has achieved commercial acceptance, in large part because of linear high shear rate viscosities achieved in blends with HEUR thickeners (Chapter 27). 

The industrial problems limiting earlier industrial thickeners in the coatings area were overcome with HEUR thickeners. With increasing sales, production limitations were addressed and the batch processes were replaced with semicontinuous techniques. Hydrophobe modification of industry standards (hydroxyethylcellulose and alkali-swellable emulsions) produced by proven industrial processes entered the market and broadened the technology. 

X HE RELATIVE COST OF MANUFACTURING hydrophobically modified, water-soluble polymers is the primary determinant in their market acceptance. The lowest-cost associative thickeners used in coating formulations are hydrophobically modified, alkali-swellable emulsions (HASE). The extensive history leading to the development of this technology is reviewed in the preceding chapter their utilization and limitations are discussed in Chapters 27 and 28. 

HASE (hydrophobically modified alkali-swellable emulsion, discussed in Chapters 25 and 28) and HEUR thickeners are readily displaced from acrylic latex surfaces (32) by sodium dodecyl sulfate (SDS). A surface-active cellulose ether was also reported (33) to desorb from monodispersed poly(styrene) latices with SDS addition. In these studies, the relative critical micelle concentrations of the anionic surfactant and thickener appear to be more important than buffering of surface charges. 

Chem. Descrip. Hydrophobically modified alkali-swellable emulsion Uses Rheology control agent for paper and paperboard coatings, esp. lightweight coatings... 

No.25,12th Dec.2000, p.9329-39 DIFFUSION OF MODEL HYDROPHOBIC ALKALI-SWELLABLE EMULSION ASSOCIATIVE THICKENERS... 

The rheological properties of hydrophobe-modified alkali-swellable emulsion (HASE) thickener solution are studied, with emphasis on surfactant and electrolyte (NaCl) effect. Similar studies in model HASE thickeners have been reported. Two commercial HASE thickeners (HASE-615 and HASE-935) are examined for comparison. In the absence of SDS, the NaCl addition changes solution viscosity depending on the relative concentration of the NaCl and thickener. The viscosities of HASE type thickeners are enhanced by an anionic surfactant, sodium dodecyl sulphate (SDS) and viscosity maxima are observed due to mixed micelle formation among thickener hydrophobes and surfactants. The addition of NaCl suppresses the viscosity of HASE-615/ SDS solutions, with HASE-935 at higher concentrations actually increasing in viscosity with NaCl addition. 2 refs. USA... 

Siu H, Duhamel J (2006) Associatimis between a pyrene-labeled hydrophobically modified alkali swellable emulsion copolymCT and sodium dodecyl sulfate probed by fluorescence, surface tension, and rheology. Mataomolecules 39 1144—1155... 

Acrylic thickeners, also known as alkali-swellable emulsions, are used to a limited extent in cheap interior wall paints. They are acids containing acrylic copolymers supplied in liquid form as an emulsion. The main limitation of these thickeners is that the thickening action is a function of the pH of the paint system and therefore the viscosity varies with pH of the system. 

Associative acrylic thickeners are also known as hydrophobically modified alkali-swellable emulsions (EASE). Chemically, they are copolymers composed of three blocks ... 

Like alkali-swellable emulsion thickeners, they are supplied as emulsions and are only active in a narrow pH range of 8 to 10, outside of which their viscosity decreases. 

HASE Hydrophobically modifled alkali-swellable emulsions... 

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