Why Will Plastic Parts Have Color Difference?
Plastic parts can be seen everywhere in daily life, but the problem of plastic parts chromatic aberration is inevitable. Only by understanding the reasons for the plastic parts chromatic aberration can we better control the chromatic aberration of plastic parts.
Why do plastic parts have color difference? How to determine the color difference of plastic parts? Plastic products are very common in life. Different plastic products will have a variety of colors. By detecting the differences in plastic colors, it is also an important means of judging product quality. This article will briefly introduce the occurrence of color differences in plastic parts.
I. The reasons for the color difference of plastic parts
Plastics are mainly polymer materials composed of synthetic resins and various plasticizers, stabilizers, lubricants and colorants. The plastic materials are generally transparent or opalescent. After dyeing, they will show various colors. However, due to the influence of different batches of raw materials and processes, it may cause color differences in plastic parts. Therefore, for manufacturers with strict color requirements, such as children's toys and medical materials. It is necessary to strictly control the color difference of plastic parts. . First, we need to understand the cause of the color difference of plastic parts:
1. Raw material factors
The characteristics of the resin itself have a great influence on the color and gloss of plastic products. Different resins have different coloring powers and some plastics have different colors. Therefore, considering the material and color of the raw materials, the coloring formula of plastics has a big impact.
The color of the raw material is also the color of the plastic. It is a factor that cannot be ignored, especially when configuring white or light-colored plastic.
Plastics with better light resistance can be formulated according to their original colors. While plastics with poor light resistance must be considered when coloring formulations are considered to change color in order to obtain good results.
2. Staining factor
At present, plastic dyeing is generally carried out by two methods: color masterbatch or dyeing granulation (toner). The colorant is the most important factor for the color difference of plastic parts. The color quality of plastic parts directly depends on the quality of the base color of the dye. Different thermal stability, dispersibility, and covering ability will cause large deviations in the color of plastic parts.
3. Processing technology
In the process of dyeing plastic parts, the temperature, back pressure of injection molding, equipment technology and environmental cleanliness will all cause large deviations in the color of plastic parts. Therefore, it is necessary to maintain the consistency of the injection molding equipment and the environment. A stable injection molding process is a key step to ensure that the color difference of the plastic parts is within the qualified range.
II. Plastic parts color difference control
Color difference control of plastic parts generally uses a colorimeter. With the continuous development of science and technology, various types of color difference verification instruments are now increasingly developed, which can effectively help companies achieve color difference management and control. The colorimeter can accurately assess the color difference between two products. It automatically compares the color difference between the sample and the tested product. Then outputs the three sets of CIE-LAB data and the four groups of ΔE, ΔL, Δa, Δb after colorimetry Color difference data.
The principle of its application is to measure the tristimulus value xyz of the sample through integration. Then calculate the chromaticity coordinates and other parameters of the sample. Usually the filter is used to cover the detector. The relative spectral sensitivity S(λ) of the detector is corrected to the spectral tristimulus values x(λ), y(λ), z(λ) recommended by CIE. When such three photodetectors are used to receive light stimuli, the tristimulus values X, Y, Z of the sample can be measured with one integration.