A problem that is more likely to occur during plastic granulation is that color difference occurs from time to time when produced according to the original formula. Many people are surprised that the same formula was qualified before, but this time it was not qualified, and even the difference was very large; or it ran off during the production process, so it was inevitable to stop and check Problem, readjust the formula, and then power on again. If you are unlucky, it is estimated that you will ride this one night or a few days, and there will be no harvest.

So, today, the editor will talk about several reasons for the color difference in the granulation process. If there are any errors, please correct me.

The color masterbatch was directly produced and pelletized without serious color testing. This is what the author has actually experienced. At that time, in order to reduce environmental pollution and reduce the cleaning time, the company decided to use color masterbatch instead of toner and modify nylon. Granulation. The replaced high-concentration color masterbatch has been tested in foreign R&D departments and the test results are qualified. Therefore, in the production process, according to the original toner ratio formula, the ratio is set according to the toner content of the masterbatch, and then the production is carried out on the production line. As a result, it was more painful. After dozens of start-up tests and shutdowns, several tons of unqualified products were produced, which is still very different from the standard samples. Finally, I had to give up. (Many people may ask, why don’t you stop and test and mix on the test line? The reason is that I don’t want to disclose too much, but it just happened.) Therefore, it is recommended to use high-concentration masterbatch instead of toner for granulation. Time. If you are not confident, please test on the test line first, and then produce on the production line after the test line is qualified. Sometimes the test line is qualified, the production line may not be qualified, and you need to deploy again. Therefore, careful color testing is a more effective method for reducing production costs and reducing waste.

There is a problem with the matching of color masterbatch and resin due to improper selection of the carrier of the color masterbatch, or the manufacturer arbitrarily changes the type of resin. The density and melt index of different grades of resin will be different, so the performance of the resin will be different, and the compatibility with the color masterbatch will also be different, resulting in a color change. Generally speaking, as long as the density and melt index are not different If the color difference is large, the color difference will not be too large, and the color can be corrected by adjusting the amount of color masterbatch.

Inaccurate measurement during use, too much or too little color masterbatch, too much or too little color masterbatch, there is a large number of random metering phenomena in enterprises, especially small and medium-sized enterprises, when weighing, the proportion, weight and variety are wrong, resulting in the color of the masterbatch produced and the standard There is a difference. These are all low-level mistakes, which can be overcome as long as they are serious. The higher the accuracy, the better the accuracy, which can reduce the occurrence of non-conforming products to a certain extent.

Plastic coloring granulation weighing balance

The heat resistance of the toner is due to the improper temperature of the machine, especially high, the color masterbatch stays in the machine for too long, which causes the toner to burn off, resulting in a difference in color. Generally, the heat resistance of inorganic pigments is relatively good and can basically meet the requirements of plastic processing, while the heat resistance of organic pigments is relatively poor. Generally, the higher the temperature, the shorter the heat-resistant time. Therefore, when the temperature of the machine is too high, the color masterbatch or toner stays in the machine for too long, causing the toner to be burned off, resulting in color difference.

The impact of the production process

1. In the baking process, ABS, PA, PC and other raw materials need to be dried before color matching. If the baking time is too long and the baking temperature is too high, the background color of the raw materials will be yellowed or discolored, resulting in color difference.

2. During the mixing process, the material tank is not cleaned and mixed with other colors, resulting in color difference; if the mixing time is not enough, other colors will be mixed to produce color difference; the mixing time is not enough or too much material causes mixing failure Uniformity also produces chromatic aberration.

3. Feeding link: The material barrel must be cleaned during refueling production, and the production must be continued after drying.