Cation latex coated

Latexes stabilized with fully ionized groups such as sulfonate ions are well known in the coatings field. But, they have not been utilized in electrodeposition because they do not cut off current. This is not the case for certain cationic latexes. An electrodeposition process based on sulfoniiim stabilized colloids has been reported (4). The sulfonium ion, like the analo-... 

Figure 3.6. Schematic representation of lonPac CSS, a latex-coated pellicular strong-acid cation exchanger (Courtesy Dionex Corp).

In HEC-thickened formulations, low-shear-rate viscosities increase with decreasing latex particle size. This effect has been a major limitation in formulating small-particle latices. The phenomenon appears to arise from electro viscous, hydration, or flocculation effects, not a depletion layer mechanism. Associative thickeners achieve efficient viscosity in coating formulations via participation in synthesis and formulation surfactant micelles to form pseudo macromolecules and via an ion-dipole interaction between the cations of surface carboxylate groups on the latex and the ether linkages of the associative thickener. Generally, an excess of synthesis surfactant is found in the production of small-particle latices. The achievement of lower viscosities in small-particle ( 100 nm) latex coatings thickened with associative thickener appears to occur by extensive disruption of the polymer hydrophobe s participation in intermicellar networks. 

Latex coating. The first objective was to cover the latex with the polycations without coagulation. Cationic surfactants as well as polycations are normally used as titrants for the determination of the charge density of anionically stabilized latexes (4). In an impropriate range of concentration, the point of charge compensation is indicated by clearly pronounced flocculation. 

Solvent emission restrictions, as for other coating systems, have also given rise to the development of water-borne, HS, radiation cured and powder PU coating systems. The various techniques which are used to obtain anionic, nonionic and cationic emulsions have been reviewed in the literature. Curing of cationic latex takes place either by reaction of water " with the terminal isocyanate groups or by reaction with water-soluble diamines according to reactions (49) and (50). 

An example of heteroflocculation between large and small particles is that between day and cationic latex. Kaolin clay fully coated by polystyrene latex (U2 = 65 nm) is shown in Figure 1.11. At lower latex dosages, less than required for full coverage, the latex acts as a cationic polyelectrolyte, flocculating the clay. This can be seen in Figure 1.12, where the stability ratio W= 1/a, is shown as a function of latex addition, together with the electrophoretic mobility of the clay. 

Poly(vinyl chloride) is commercially available in the form of aqueous colloidal dispersions (latices). They are the uncoagulated products of emulsion polymerisation process and are used to coat or impregnate textiles and paper. The individual particles are somewhat less than 1 p,m in diameter. The latex may be coagulated by concentrated acids, polyvalent cations and by dehydration with water-miscible liquids. 

Serizawa and Akashi [95] analyzed the monolayer adsorption of polystyrene latex particles with cationic polyvinylamine grafted on their surface, while Serizawa et al. [96,97] used commercial anionic latex particles. Both types of particles were adsorbed on polyelectrolyte-coated substrates previously prepared by alternating adsorption of cationic and anionic polyelectrolytes such as polyallylamine hydrochloride (PAH) and polystyrene sulfonate sodium salt (PSS) according to the method described by Decher [164]. Using... 

Using a similar procedure, it was also possible to coat cationic and anionic latexes with zirconium hydrous oxide (145). On careful heating such powders in air at temperatures >500°C the core polymer was vaporized and the shell was calcined to yield hollow spheres of Zr02, as illustrated in Figure I.1.21B (145). 

NC. mar Latex] NR latex for extruded thread, carpet backing, latex foam, dipped goo coatings, medkal qtpli-cations, textil adhesives. 

Another strategy consists in the use of QDs coated with a cysteine acrylamide, a polymerizable stabilizer [304]. Successful incorporation of hydrophilic cysteine-acrylamide-stabilized QDs into 80-200 nm fluorescent latexes was achieved via emulsion polymerization, as reported by Sherman et al. [308], using two different procedures. In the first, a two-step shot growth surfactant-free emulsion polymerization of styrene and NaSS was performed in the presence of a solution of hydrophilic cysteine-acrylamide-stabilized CdS or CdSe/CdS QDs. In the second approach, CdSe/CdS QDs were first electrostatically modified by vinylbenzyl(trimethyl)-ammonium chloride and subsequently copolymerized with styrene in the presence of SDS. A third approach was also described in this paper coating of cationic PS particles with anionic poly(cysteine acrylamide)-coated QDs through electrostatic-driven interactions. 

Uses Antifoam for waterborne industrial and cationic coatings Features Letdown antifoam good for difficult-to-defoam systems Properties Off-wh. opaque dens. 7.8 Ib/gal flash pt. (PMCC) 160 F Use Level 0.5% (latexes), 0.75% (water-reducibles), 0.25% (solv.-based coatings/adhesives)... 

Uses Crosslinking agent for carbo) ated SBR latex, carbo) methyl cellulose, PVA, and other water-sol. polymers water resist, aid for starch-based adhesives and coatings food-contact paper/paperboard Regulatoty FDA 21 CFR 176.170,176.180 Preperties Pale amber liq. water-soL sp.gr. 1.12 vise. 325 cps f.p. -6.7 C pH 4.5 cationic 35% total solids Staage 100 days shelf life below 32 C Pdyfluo 120 [Micro Powders]... 

---