Color difference is a common defect in injection molding. There are many factors affecting color difference, including raw material resin, color masterbatch, mixing of color masterbatch with raw materials, injection molding process, injection molding machine, etc.

ABS plastic injection molding products can be seen everywhere in our daily lives. In order to use products to have a good appearance and visual effect, appearance parts are required to have different colors, parts that constitute appearance of equipment are required to have consistent colors. Chromatic aberration is one of common defects in colored ABS plastic material injection molding products. Such defects will cause product color differences and seriously affect product quality. Now analyze influencing factors and solutions of chromatic aberration:　
1) Different batches of ABS plastic materials have a certain color difference, color difference between some batches has exceeded 0.8 control index required by cooperative user.
2) Adding different batches of color masterbatch with same batch of ABS natural color material will produce larger color difference. When using same batch of color masterbatch to add different batches of ABS natural color material, it will also produce larger color difference. Adding same batch of color masterbatch to a batch of natural colorants will have smaller color differences. It shows that batch difference between ABS and color masterbatch will have a greater impact on color difference of injection molded products.
3) Color difference of premix injection products (granulated by twin screw) is smaller than that of admixture (mechanical mixing), and mixing effect will affect chromatic aberration.
4) Back pressure has little effect on chromatic aberration. Increasing screw speed has little effect on chromatic aberration, but if screw speed is too low, stopping time will be longer and chromatic aberration will be more serious.
5) Injection temperature and residence time have a great influence on color difference.
6) Dilution ratio of color masterbatch has a certain effect on color difference, reducing dilution ratio can improve mixing effect of admixture.
7) Increasing dispersant in color masterbatch can reduce color difference of injection molded products.
In view of color difference problem in application of ABS plastic raw material injection molding products, following solutions are proposed:
1) Sampling inspection of raw materials (ABS resin and color masterbatch), if there is a large color difference between batches, mix raw materials in batches.
2) Do not use a small injection molding machine to make large products to ensure that material has enough time to plasticize evenly in barrel.
3) Reduce material stopping time in barrel and do not use large machines to make small parts; control temperature of nozzle and thickness of material cushion of melt after injection. Thickness of material pad is preferably 1~1.5 mm to prevent melt from being heated for a long time to affect color difference of product.　
4) Appropriately reduce dilution ratio of color masterbatch.
5) In manufacture of color masterbatch, amount of dispersant can be appropriately increased to strengthen dispersion of color masterbatch in matrix resin.
6) Increase amount of antioxidants in both ABS plastic raw materials and color masterbatches to improve thermal stability.
7) When color masterbatch is used for coloring, because density of color masterbatch is greater than that of original color, color masterbatch will be stored in barrel for a long time, and will gradually precipitate downward, resulting in generation of color difference. Therefore, each time hopper of injection molding machine is fed, feeding amount should be controlled as much as possible.