Resins latex agglomerated

Over the years, Dionex has developed a wide variety of latex agglomerated resins to meet various needs in IC. A review of these developments is given in a book by Weiss [16]. Properties of latex columns are summarized in Table 3.6. 

Table 5 Selected columns based on the latex-agglomerated resins.

In the latex, the resin may be present as particles as small as 0.2 yum (0.0002 mm) in diameter. On spray drying, some form of agglomeration takes place to yield resins with particle diameters in the 1-2//m (0.001-0.002 mm) range. Thus the dry emulsion-produced resins are approximately one hundredth the size of suspension polymers. On the other hand, this method of manufacture frequently requires the use of relatively large quantities of surfactants, which remain adsorbed on the particle surface. 

In choosing an epoxy and polymeric latex, it is important that they have compatibility. Incompatibility usually occurs when the pH of the epoxy resin dispersion alters the pH of the latex into a range where the ionically stabilized latex is broken, causing agglomeration of the latex polymer. The pH of the epoxy resin s emulsion may need to be adjusted before blending with the polymeric latex. 

The agglomerating methods described above are economical, reliable, and effective and have been used in the production of impact-resistant resins. But the mechanism and the characteristics of these agglomerating processes have not been reported in the literature therefore, in this chapter, the behavior and the mechanism of agglomeration was studied using poly(n-butyl acrylate) as the agglomerated latex A, and n-butylacrylate-acrylic acid copolymer as the agglomerating latex B, based on the interaction between hydrophilic free polymer and polymer latex. 

To achieve concentrations above 50% it is necessary that at least a portion of the polymer be present in agglomerates of greater than colloidal size. In a latex, the polymer is present in the form of globules existing as a discrete phase in an aqueous matrix. Natural and synthetic rubbers, vinyl resins, and acrylics are the most important of the adhesive latexes. The polymer is not limited in molecular weight since the viscosity does not depend on what is contained within the discrete particles. The viscosity of the latex depends primarily on solids content and the composition of the aqueous phase. Latexes are commonly available in concentrations of 35 to 55% but it is possible, in some cases, to go considerably higher before reaching an excessive consistency. 

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