Color measurement of plastic pellets with the Aeros – routine analysis

Rapid routine analysis in the production of plastic granulate is important in order to detect whether the color of the product is correct at an early stage in the process. Particularly in the case of translucent granules, close attention is paid to the degree of yellowness (Yellowness Index YI). This allows you to intervene in the process in good time to ensure the correct color of the end product. Due to the non-uniform surface of the pellets, it is important to measure as large a surface as possible. Of course, the measuring process should be as simple as possible and not hold up the production process.

Color-measurement-of-granules-colored-HunterLab-AerosThe task

Since pellets have a non-uniform surface, the largest possible surface area must be examined during color measurement. With the usual measurement via the bottom of a glass cuvette, this area is usually not large enough to obtain repeatable measured values. For this reason, several individual measurements must be averaged for smaller measurement areas. It is therefore desirable to measure as large a surface area as possible without complications. In addition to the color values L*, a* and b*, the industry-standard Yellowness Index should also be determined directly.

The solution

HunterLab specifically recommends non-contact color measurement with the Aeros spectrophotometer for the color measurement of plastic pellets. The sensor of the Aeros sits eccentrically above the edge of a bowl with which a larger quantity of pellets can be easily scooped, for example. During the measurement, the device automatically sets the correct height above the sample and the pan rotates once under the sensor. In the process, 35 measurement flashes are triggered in five seconds and averaged to produce the result. This means that a measuring area of approx. 177 cm2 is evaluated in a single process, which means that this measurement corresponds to approx. 20 conventional individual measurements in a cuvette and is therefore very representative. The device then outputs the color values and the desired indices, such as the Yellowness Index, directly on the integrated touchscreen.

The measurement – very simple

  • Pour the pellets into the bowl
  • Place the bowl on the turntable
  • Trigger measurement at the touch of a button
  • Read the values on the screen after 5 seconds

The blog about color measurement

All about color measurement

The HunterLab Europe company blog keeps you up to date on applications and measurement methods, product presentations and company news. Our spectrophotometry experts regularly give you an overview of the colorful and diverse world of color measurement.
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