Electrodeposition paints properties

Effect of Solvents on Properties of Latex and Electrodeposition Paints... 

Certain components of domestic appliances are also coated with electrodeposition paints. Two-pack polyurethanes are applied if the dimensions of the parts are too large for the electrodeposition bath. These paints dry at ambient temperature to give films with similar properties to stoving acrylic enamels. Solvent-free powder coatings are also used to coat domestic appliances. Nowadays powder coatings and precoated metal (coil coating) are gaining more importance. 

One of the main differences of electrodeposition paints with conventional water soluble paints is their lower solids and thus solvent content. A typical binder content is around 10%w, the amount of solvent approximately 5%. The rest, apart from pigmentation, is water. The influence of solvent in the early stages of binder/paint formulation is very similar to the effects described for conventional aqueous paints which is also started from an approx. 70% solids binder solution in coupling solvent(s). The choice of the solvent (blend) is, however, less influenced by its evaporation characteristics as the deposited paint film does not contain much water and is stoved after application. Of more importance are paint stability and electrical properties (conductivity, rupture voltage). 

Recently a cationic electrodeposit paint with better anti-corrosion properties has been developed and is replacing anionic electrodeposit paint. This has made it necessary for the ultrafilter maker to develop a new ultrafiltration membrane, because conventional membranes suitable for anionic electrodeposit paint suffer some decline in filtration rate with the passage of time, when they are used for cationic electrodeposit paint. This problem has been solved by developing a modified membrane for cationic electrodeposite coating. This new membrane shows better flux stability than the conventional type. 

The addition of an alcohol before, during or after the neutralization results in an aqueous coating composition [181] that can form films that are not only superior in the resistance to corrosion and to water, but also have favorable physical properties such as hardness, adhesion, impact strength, and flexibility. They show excellent draining properties in electrodeposition paint and exhibit a remarkably improved performance in comparison with paints based on other LMWPBs such as cis-1,4-polybutadiene as the starting material [182]. 

The binders for cathodic electrodeposition are epoxy resin combinations dispersed in water (see Section 3.8). Advantages of anticorrosive electrocoatings include excellent corrosion resistance at a dry film thickness of ca. 20-30 pm. Electrocoats are stoved at 165 -185 °C to obtain films with the desired properties. The paint industry is now developing electrocoats that can be cured at lower temperatures (140 150 "C). Electrocoating produces a homogeneous film that covers the entire car body surface, including recesses and cavities. 

Uses PVC plastisol adhesion promoter for automotive sealants applied to visible areas and anti-chip primers adhesion promoterfor electrodeposition primers used in mfg. of automobiles, tmcks, and buses Features Wet-on-wet paint capabilily 120 C cute exc. color stabilily Properties Clear vise, liq. vise. 300-500 poise flash pt. (OC) > 100 C Use Level 4-6 parts... 

The binder properties are useful in other pigmented coatings such as clay-based paints (119). The zinc-lithium silicate coatings can be applied by anodic electrodeposition on steel (120). In another-typc of use, lithium polysilicate provides an intermediate bond between the fluorocarbon polymer coating and metal on antisticking cook ware (121). 

Similar to the Types la and lb fibers, the Type Ic fibers consist of a thin, conductive metal layer electrodeposited upon a carbon base fiber (see Figure 5). Their manufacture is described by Morin(27) and by HaU and Ando(25). The paper by Hall and Ando provides a good overview of their properties and characteristics. Nickel plated exPAN carbon fiber are typical of the Type Ic fibers that are readily commercially available. General uses for Type Ic fibers are in ESI shielding, conductive adhesives and paints, conductive fabrics, and high performance electric contacts(2P). They are included in the Type 1 category because their conductivity is characteristically metallic. Thus, by this convention they appear in the Type 1 classification while the various other carbon fibers fall into the Type 2 category. 

Whilst there are some thermoset acrylic emulsions cormnerdally available, the bulk of the thermoset resins, used as the main binder system, are produced in solution. Some may then be made waterborne by neutralisation and inversion (dispersion) into a water phase. Lower molecular weights favour this qrproach. The rate of conversion from solvent based to waterborne industrial thermoset coating systems has been, and is, much slower than the conversion from architectural alkyd paints to emulsion altonatives. There are two principle reasons for this. Firstly there are problems of application and substrate wetting of many waterborne systems. Secondly, the modifications frequently required to induce water dispersibility reduce one or more of the essential performance properties required from the cured film, compared to a solvent based system. Water resistance, with many films having an increased tendency for blushing is one example. However, for some applications, such as electrodeposition, only waterborne systems will work. 

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