Manufacture of Powder Coatings
Technical Main Page, Technical Datasheets, Guaranteed Performance, Technical Manual, Application Process, Manufacture of Powder Coatings
There are 5 key stages in the manufacture of powder coatings.

Formulation:
The formulation of powder coatings involves the use of 4 basic raw material types: resins, pigments, curing agents and additives. Resins provide strength, durability and adhesion; pigments add colour; curing agents cause the resins bond to the substrate and harden; additives are used to enhance the coatings properties, such as improving flow-out or application properties.
All raw materials used in Synthatec products have been carefully selected and thoroughly tested to ensure that they meet the rigorous demands of the architectural market.


Artificial weathering testing at Valspars in-house facility.

Cooled extrudate entering the 'kibbler'.

Premix:
Once a product has been formulated and is ready for manufacture, raw materials are carefully weighed and measured. These raw materials are then blended together, either by high-speed mixing or tumbling, to ensure a consistent dispersion of raw materials throughout the mixture.

Extrusion:
The mixed raw materials are then fed into an extruder. The extruder applies pressure and heat to melt the resins and thoroughly incorporate the pigments, curing agents and other ingredients into a homogenous substance.
The extrudate is cooled and chipped, reading for quality checking and micronising.

Micronising:
Once the extrudate has been cooled, chipped and quality checked it is ready for micronising. Micronising grinds the chip into a fine powder. This powder is sieved and classified to ensure an even particle size distribution. Particles which are under 10 micrometres or above 120 micrometres in size can cause application problems and are removed by the sieving and classification process.


Valpars automated micronising and box filling system.


Spraying test panels in the QC department

 

Quality Control:
Quality control checks are made at both the extrusion and micronising stages of the manufacturing process.

Extrusion stage: Chip from the extruder is ground and the resulting powder applied to test panels. The following tests must be passed before production continues:

  • Film Thickness - the thickness of the cured coatings is checked to ensure that it meets the appropriate specification for further testing.
  • Colour - colour is checked both visually and by computer against the standard and the last batch to ensure that there is no colour variation.
  • Gloss - panels are tested to ensure that the gloss level meets the specification for the product.
  • Mechanical Impact - Test panels are subjected to a 20"/lb mechanical impact with no cracking or loss of adhesion.
  • Visual surface inspection - panels are inspected visually for contamination and inclusions in the coating.

Micronising stage: Finished powder from the microniser is applied to test panels. The following tests must be passed before product is placed into stock:

  • Film Thickness - the thickness of the cured coatings is checked to ensure that it meets the appropriate specification for further testing.
  • Colour - colour is checked both visually and by computer against the standard and the last batch to ensure that there is no colour variation.
  • Gloss - panels are tested to ensure that the gloss level meets the specification for the product.
  • Mechanical Impact - Test panels are subjected to a 20"/lb mechanical impact with no cracking or loss of adhesion.
  • Erichsen Cupping - A ball bearing is mechanically forced into the surface of the panel, creating a 'cup' on the surface, testing the flexibility and adhesion of the coating under sustained pressure. Products must pass this test with a 7mm cupping and no cracking of the coating.
  • Particle size - particle size is important to ensure consistent, high quality application of the product. A computerised laser scanning particle size measurer is used to ensure that less than 10% of particles < 10 microns, less than 3% > 120 microns, and the majority are between 34 and 42 microns.
  • Visual surface inspection - panels are inspected visually for contamination and inclusions in the coating.

Mechanical impact testing
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