Resins electrodeposition

The solvents used for electrodeposition resins perform three functions. First, the solvent facilitates handling during the preparation of the aqueous solution since these carboxyl containing materials are either resinous or sticky semi-solids. Second, the solvent may accompany the vehicle during deposition and therefore can influence the flow characteristics during post-deposition bake or cure. Third, the solvent can confer better water solubility characteristics on the resin and thus help to maintain bath stability, a factor of prime importance in electrocoating. 

Despite the importance of solvents in electrodeposition, technical literature on the subject is sparse. To the authors knowledge there have been only two publications on this subject (I, 2). There is also a third, unpublished (3) effort which indicates that the glycol ethers are a particularly useful class of solvent. However, all of these studies are narrow in scope in that only one electrodeposition resin was used in each case. The present study encompasses three of the more popular resin system. ... 

If the dispersed, electrodepositable resin is symbolized as RC00 + , it is implied that the RC00 moiety will be removed from the bath in the form of a paint coat that is anodically deposited on the workpiece. If the solubilizer moiety would remain in the bath, it would accumulate and eventually interfere with the coating operation. 

Pampouchidis et al. (83A.B) also synthesized urethane-based cationic electrodeposition resins. 

Electrodeposited resins based on epoxy resins can be of both the anodic and cathodic types. The anodic types based on maleinized epoxy esters have already been mentioned in this chapter. Cathodic electrodeposition resins may be illustrated by the reaction product of epoxy resin with diethylamine ... 

Block copolymer latexes Electrodeposition resins Light-curable compositions Synthetic drying oils Corrosion-resistant electrodeposition coatings... 

Toxic substances adsorbed on resins are removed during a regeneration procedure. The resulting spent regeneration solution has a higher concentration of the toxic substance than the stream from which it was removed by the resin. Toxic material in the spent regenerating solution can usually be precipitated, electrodeposited as in an electrolytic ceU, or made insoluble by other acceptable procedures. 

Significant advances in waterborne coatings have been made by PPG Industries utilizing epoxies as co-resins. These coatings are used in cathodic electrodeposited systems, widely accepted for automobile primers. Many patents have been issued for this important technology (50,51). 

After rinsing and dry-off, the primer is applied. In most modern plants this means electrodeposition of the primer (Section 14.1). The most widely used primers are cathodic. The body shell is made the cathode and current flows between it and inert anodes in the electropaint bath. The paint is formulated so that the resin is basic and, when neutralised with an acid such as lactic acid, becomes positively charged. The most widely used resins are epoxy-amine adducts ... 

Applications Electrodeposition of cationic paint resin on automobiles (connected to the cathode) provides a uniform, defect-free coating with high corrosion resistance, but carries with it about 50 percent excess paint that must be washed off. UF is used to maintain the paint concentration in the paint bath while generating a permeate that is used for washing. The spent wash is fed back into the paint path (Zeman et al., Microjiltration and UltrajUtration, Marcel Dekker, New York, 1996). 

Bone Sample wet ashed, spiked with 243Am, and purified by anion exchange resin column, solvent extraction, and electrodeposition a -Spectrometry No data 98% Mclnroy et al. 1985... 

Sediments Sample leached with HNO3/HF, filtered, purified by KL-HDEHP resin columns, solvent extracted, and electrodeposition a -Spectroscopy No data 95-99% Guogang et al. 1998... 

Various methods ofachieving preconcentration have been applied, including Hquid -hquid extraction, precipitation, immobihzation and electrodeposition. Most of these have been adapted to a flow-injection format for which retention on an immobihzed reagent appears attractive. Sohd, sihca-based preconcentration media are easily handled [30-37], whereas resin-based materials tend to swell and may break up. Resins can be modified [38] by adsorption of a chelating agent to prevent this. Sohds are easily incorporated into flow-injection manifolds as small columns [33, 34, 36, 39, 40] 8-quinolinol immobilized on porous glass has often been used [33, 34, 36]. The flow-injection technique provides reproducible and easy sample handhng, and the manifolds are easily interfaced with flame atomic absorption spectrometers. 

The grinding tools can be classified by their binder phase as resin bonded, ceramic bonded, or metal bonded (sintered or electrodeposited). 

The modem process of electrodeposition can thus be described as a combination of three basic elements (a) Electrophoresis - migration of charged polymer particles to metal surface (b) Deposition - colloidal de-stabilization of particles at the metal-bath interface and (c) Insulation - formation of an adherent, non-conductive layer of resin on the metal surface. The last named element is responsible for the high throwing power which can be achieved with the electrocoating process. 

The H and OH" ions are supplied by the simultaneous electrolysis of water during electrodeposition. Electrode reactions involving the resins are of little significance. However, oxidation of the metal substrate does play a role in anodic electrocoating. 

Development of Epoxy Resin-Based Binders for Electrodeposition Coatings with High Corrosion Resistance... 

Electrodeposition (EE ) has proved to he a most attractive process for industrial coating, in particular for the priming of automobile bodies. Epoxy resins play a leading role in this field, nearly 6 % of all epoxy resins sold for coatings being used in ED systems. 

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