7.13.3.3 Roller Coating
This method is used to coat coils and sheets by passingt hem through two
rollers. The thickness of paintfilm is controlled by adjustingthe rollers. Oneside or both-sidescoating is possible.
7.13.3.4 Powder Coating
Because of the absence of organic solvents, powder coatings have grown in
popularity as antipollution coatings. Coating thicknesses of 25–250 m mc an
be obtained. Automotive bodies, electric components, housing materials,
wires, and cables make use of this method. Polyethylene and epoxy resins
are the predominent types of paints used. At the present time, the following
eleven procedures are used in this coating process:
1. Pouring method (flock coating)
2. Rotational coating of pipes
3. Fluidized bed
4. Dipping in nonfluidizing powders
5. Centrifugal casting
6. Rotational molding
7. Electrostatic Powder spraying
8. Electrostatic fluidized bed
9. Pouring or flowing of fluidized powder
10. Electrogasdynamics powder spraying
11.F lames praying of thermoplastic powders
7.13.3.5 Electrodeposition
The anodic deposition process forp aintc oating systems was introduced
in the early 1960s and the cathodic deposition system in 1972. Electrodeposition processes are widely used since they possess the advantages of
unmanned coating, automation, energy saving, and lower environmental
pollution. This process is used to apply coatings to automotive bodies
and parts, domestic electric components, machine parts, and architecturals
such as window frames.S chematici llustrations of anodic and cathodic
electrodeposition of paints are shown in Figure 7.22.
The primary paints used in the electrodeposition process areanionic type
resins with ac arboxyl group (RCOOH, polybutadiener esin) and cationic
type resin (R–NH 2 ,e poxy resin). Hydrophilic groups and neutralizing
agents area dded to the water insolubleo ru ndispersed prepolymers to
convert them to soluble or dispersedm aterials.
The dissolution of metal substrate in the cathodic process is much less
than that in the anodicp rocess. The primary resins used in the cathodic
Coatings
473
CAT8247—CHAPTER 7—17/10/2006—15:04—TRGANESH—XMLM ODEL B–pp. 403–485
This method is used to coat coils and sheets by passingt hem through two
rollers. The thickness of paintfilm is controlled by adjustingthe rollers. Oneside or both-sidescoating is possible.
7.13.3.4 Powder Coating
Because of the absence of organic solvents, powder coatings have grown in
popularity as antipollution coatings. Coating thicknesses of 25–250 m mc an
be obtained. Automotive bodies, electric components, housing materials,
wires, and cables make use of this method. Polyethylene and epoxy resins
are the predominent types of paints used. At the present time, the following
eleven procedures are used in this coating process:
1. Pouring method (flock coating)
2. Rotational coating of pipes
3. Fluidized bed
4. Dipping in nonfluidizing powders
5. Centrifugal casting
6. Rotational molding
7. Electrostatic Powder spraying
8. Electrostatic fluidized bed
9. Pouring or flowing of fluidized powder
10. Electrogasdynamics powder spraying
11.F lames praying of thermoplastic powders
7.13.3.5 Electrodeposition
The anodic deposition process forp aintc oating systems was introduced
in the early 1960s and the cathodic deposition system in 1972. Electrodeposition processes are widely used since they possess the advantages of
unmanned coating, automation, energy saving, and lower environmental
pollution. This process is used to apply coatings to automotive bodies
and parts, domestic electric components, machine parts, and architecturals
such as window frames.S chematici llustrations of anodic and cathodic
electrodeposition of paints are shown in Figure 7.22.
The primary paints used in the electrodeposition process areanionic type
resins with ac arboxyl group (RCOOH, polybutadiener esin) and cationic
type resin (R–NH 2 ,e poxy resin). Hydrophilic groups and neutralizing
agents area dded to the water insolubleo ru ndispersed prepolymers to
convert them to soluble or dispersedm aterials.
The dissolution of metal substrate in the cathodic process is much less
than that in the anodicp rocess. The primary resins used in the cathodic
Coatings
473
CAT8247—CHAPTER 7—17/10/2006—15:04—TRGANESH—XMLM ODEL B–pp. 403–485