Color matching technology in powder coatings

Broadly speaking, coatings provide two distinct properties: protection of objects and aesthetics consisting of desired color, gloss and surface properti.

Definition and Properties of Pigments

Pigments are insoluble fine particles that provide color and provide hiding by dispersing in a medium (in this case a powder coating binde.

Because pigments are composed of relatively fine particles, their natural state tends to aggrega.

Pigments used in powder coatings are classified into two categories: organic and inorganic in natu.

Classification

Colorant pigments are usually classified by color index numbe.

Precautions for color matching practice

Achieving a specific color effect depends on the details of the basic recipe principles described bel.

Start with an excellent range of pigments

When color matching, avoid using the wrong pai.

It is best to start the experiment on a clean plate with the pigment that will achieve the highest color goal and provide the closest durabili.

keep things simple

As a general rule, 2 (or less), but no more than 3, colored pigments are added to black or white pigments (as neede.

Determine the necessary pigment concentration based on the desired hiding power

When color matching, the most important thing is to determine the pigment concentration in order to achieve acceptable hiding power according to the required thickne.

Another reason to apply the correct pigment concentration is co.

Formulation and performance judgment

When choosing pigments for color matching, it is important to pay attention to the following topics:

heat resistance

The powder coating mixture is exposed to the heat source at least three tim.

Thermal stability data provided by pigment suppliers should be carefully reviewed prior to application in formulatio.

Powder coating formulations that require exceptionally high temperature resistance during the service period need to consider special formulatio.

UV resistance

The UV resistance of all materials depends on their chemical compositi.

The best guide documents for UV resistance come from supplie.

Lightfastness is resistance to UV light only and can be measured using the accelerated weathering method with or without the addition of other accelerated environmental factors such as humidity and temperatu.

Weatherability refers to durability in real-world environments and covers all factors that a surface coating will encounter in service, including UV light, moisture, temperature, acidic and alkaline airborne compounds, and di.

In general, metal mixed oxides provide the greatest weather resistan.

These pigments consist of a very stable crystal structure that resists UV light and various chemicals and heat exposu.

And some automotive grade organic pigments also have very good weather resistan.

toxicity

Most pigments used in powder coatings are relatively nontox.

Before choosing any pigment, however, be sure to consult the supplier for additional safety data files for that pigment to ensure that the product is safe for the end us.

food contact

The.


Food and Drug Administration (FDA) lists pigments suitable for use in polymers that can come into contact with fo.

This information can be found in Code of Federal Regulations (CFR) 21 Part 17329

hiding power

Hiding power (sometimes referred to as "shadowing") refers to the ability of a coating to reduce the transfer of visible light from the substrate under the coati.

Certain coatings provide measurable hiding power at certain thickness.

The formulation must provide enough pigment to fully cover the substra.

The hiding power of powder coatings can be measured by applying special black or white metal flakes after heating and crosslinking in an ov.

These standard test pieces are coated to a certain thickness on a black or white surfa.

The percent hiding power can be calculated by calculating the color contrast (reflection) of a white-coated surface versus a black-coated coating according to ASTM D-6441: Determination of Hiding Power of Powder Coatin.

At a given thickness, hiding power is expressed as a percentage (eg, at 5 mils, 90%) or as the minimum thickness at a given hiding power (eg, 90% coverage, 2 mils minimu.

95% coverage is generally considered the minimum standard, however 90% is best for color consisten.

proportion

Specific gravity is also expressed as density, which refers to the weight per unit volume of a substance, generally expressed in grams per millilit.

The specific gravity of colored pigments ranges from 2 toOrganic pigments are generally less important than inorganic pigmen.

Specific gravity affects the weight of the pigment in the formulati.

High specific gravity pigments occupy less volume in powder coatings and generally require higher weight percentages to provide color and hiding pow.

This results in a higher specific gravity of the powder coati.

High specific gravity powder coatings provide less coverage per unit weight than low specific gravity powder coatin.

This affects the economics of the pai.

cost

Cost is an important judgement factor when considering any powder coating formulati.

Raw material cost is an obvious factor, but tinting strength, specific gravity, and processability all contribute to the final co.

Pigments with poor tinting strength and hiding power require higher values ​​in the formulati.

That would exceed the minimum price per pound of pai.

Pigments that require intensive (or special) treatment will also increase the final cost of the produ.

This may be due to poor dispersion or poor consistency of the pigme.

The color matching of powder coatings is a complex challenge, requiring a solid technical foundation and an eye that is sensitive to both color and chromatic aberratio.

In most cases, if you follow the four principles of simplicity, durability, hiding power and cost, there will be fewer mistakes in specific operations