Coating powders binders

We have been seeking a method for synthesizing oligomeric LC polyols that could be adapted to economical production. Reactions of p-hydroxybenzoic acid (PHBA) were investigated. PHBA is commonly used as a monomer in LC polymers (3-A), and its use in binders for powder coatings has been described. (8-11). 

Table 3.4 summarizes the consumption of thermosetting binders used in various regions. The epoxy-polyester systems predominate over polyester-trisglycidyl iso-cyanurate and epoxy systems. The consumption of thermoplastic coating powders, particularly those used in the fluidized-bed and flocking processes, is substantially lower than that of thermosetting powders (Table 3.5). Their production does not show a comparably significant growth rate.

Table 3.4. Production of thermosetting coating powders in 1995 classified according to binder types...

The typical constituents of a coating powder are binders (resins, if necessary hardeners and accelerators), colorants (mainly pigments), additives, and in some cases extenders. 

DIN 55690 classifies and identifies coating powders according to the binder. Standards for testing coating powders in powder form are summarized in Table 3.9. Relevant European standards (CEN) have not yet been drafted. Quality aspects are described in detail in [3.50]. 

The unsaturated polyester resins are used as fire retardants, binders, and powder coatings [79], and in the reinforced plastics industry. Fire-retardant polyester resins generally contain halogen in the acid or glycol component, or other... 

Vacuum metallization and metallized films Coatings derived from dispersion of conductive fillers such as carbon black, metal powders, and flakes in polymeric binders Coatings derived from solutions of antistatic materials such as quaternary ammonium compounds, ethoxylated amines, amides, and other antistatic materials that function by absorbing atmospheric humidity... 

A fluidized bed method is used to apply relatively thick thermoplastic powder coatings. The article to be coated is heated above the Tg of the binder resin and then suspended in a fluidized bed of coating powder. Powder particles fuse onto the object imtil the powder layer becomes sufficiently thick to act as a thermal insulator and prevent additional fusing. Since the surface may contain incompletely fused particles, the operation is completed in a separate oven. Electrostatic fluidized beds are also used, with charged powder and grounded substrates, which may or may not be preheated. 

Furman, V.V., Gaiduchenko, G.K., Vlastuk, R.Z. and Oeimontovich, V.B., Structure and properties of electrophoretic chromium carbide coatings with a eutectic composition nickel-boron binder, Sov. Powder Metall. S Met. Ceram. 22 942-45 (1983). 

Metal powder—glass powder—binder mixtures are used to apply conductive (or resistive) coatings to ceramics or metals, especially for printed circuits and electronics parts on ceramic substrates, such as multichip modules. Multiple layers of aluminum nitride [24304-00-5] AIN, or aluminay ceramic are fused with copper sheet and other metals in powdered form. The mixtures are appHed as a paste, paint, or slurry, then fired to fuse the metal and glass to the surface while burning off the binder. Copper, palladium, gold, silver, and many alloys are commonly used. 

Binders in Ceramics, Powder Metallurgy, and Water-Based Coatings of Fluorescent Lamps. In coatings and ceramics appHcations, the suspension rheology needs to be modified to obtain a uniform dispersion of fine particles in the finished product. When PEO is used as a binder in aqueous suspensions, it is possible to remove PEO completely in less than 5 min by baking at temperatures of 400°C. This property has been successfully commercialized in several ceramic appHcations, in powder metallurgy, and in water-based coatings of fluorescent lamps (164—168). 

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