How can color sensors distinguish different types of plastic?

The growing amount of plastic waste worldwide poses a huge challenge to the recycling industry. Identifying and sorting different types of plastic is critical to achieving efficient recycling processes.
Requirements within the plastic recycling industry for producers and end users are constantly being tightened. In the near future, a finished plastic product will have to contain at least 55% recycled plastic.
In addition, plastic quality requirements are being tightened. In the coming years, end users will be required to package food and beverages in plastic that is 95% composed of recycled material not previously used for non-food items.
These stricter standards bring challenges in delivering the desired products. The more recycled plastic is used, the more challenging it becomes to maintain exact color. This highlights the increasing importance of accurate color measurements in the future.
For the plastic recycling industry, the more thorough the sorting at fine detail level, the greater the quality of the final product. Precise control of both quality and color is vital within this industry.
An emerging technology that is revolutionizing this are color sensors. These innovative sensors use advanced optical techniques to distinguish different types of plastic based on their color.
The recycling industry plays a vital role in reducing plastic waste and conserving natural resources. However, traditional sorting techniques are time-consuming and labor-intensive, resulting in inefficient waste separation. Moreover, polluting streams of plastic continue to accumulate, highlighting the need for innovative solutions.
Color sensors are advanced optical sensors that operate on spectrometric principles. They can analyze the light reflected from a surface and identify the unique wavelengths of light absorbed by the material. This allows them to accurately determine the color of the plastic and identify the type of plastic.
Color sensors are used in various recycling facilities for sorting various plastic materials, such as PET, HDPE, LDPE and more. They can also be used in other industries where color identification of materials is important.
The following describes application areas in which color sensors are particularly effective for the plastic recycling industry.
Color sensors are excellent for measuring colors on colored plastic parts. Even when the surface is shiny, this can be overcome by using a light input at a 45-degree angle along with a diffuse beam for a wider measurement range. This allows sensors to detect colors on objects with various shapes and shiny surfaces.
Identifying and measuring color differences on shiny objects such as colored plastic can be challenging. However, using a 45-degree inclination angle and a diffuse beam over a larger measurement area makes this possible. This allows sensors to measure or detect colors on objects with different shapes and shiny plastic surfaces.
A specific challenge here is being able to see through plastic films. By reducing gloss and placing a white background, this problem can be solved. This allows the colors of films to be measured in production environments, allowing any errors in printing to be detected.
Color measurements are performed using a light spot, which must be large enough for reliable measurement. Even objects with a diameter of only 1-2 mm can be measured thanks to different optics that provide a focused light beam and thus a very small light spot (diameter of 0.3 mm). This makes it possible to measure colors on relatively small plastic objects.
Conclusion: Color sensors represent a promising innovation in the recycling industry, enabling more efficient and sustainable processes. By better differentiating plastic waste, these sensors help reduce pollution and promote a circular economy. With continued technological advances and investments in the recycling industry, color sensors can play a key role in realizing a cleaner and greener future.
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