Color Problems of TPE / TPR material injection
Color injection molding defects common situation because the color difference caused by fittings injection molding machine is not small batches see scrapped. Color influenced by many factors, involving raw material resin, masterbatch, masterbatch mixed with the raw materials, injection molding process, injection molding machines, molds, etc., because of extensive involvement surface, so the color control technology is also recognized as difficult to master one of injection molding technology. In the actual production process, we are generally carried out in the following six aspects of color control.
1. eliminate the influence of injection molding machines and molds factors
To select the main goods and injection capacity considerable injection molding machines, injection molding machines, if the presence of dead material and other issues, it is best to replace the equipment. For the die casting system, exhaust ducts caused by chromatic aberration, can be solved by the corresponding part of the mold maintenance mode. Must first solve the problem of injection molding machines and die before they can organize production, to reduce the complexity of the problem.
2. eliminate the impact of raw material resin masterbatch
Control of raw materials is the key to solve the color difference. Thus, in particular, the production of light products, can not ignore the raw resin thermal stability of products in different color fluctuations significantly affected. Given that most of injection molding manufacturer does not manufacture or masterbatch plastic masterbatch, so that may be the focus of attention on production management and materials testing. Namely strengthening the raw material storage test; the production of the same product as far as possible the same manufacturer, same grade masterbatch, masterbatch production; for masterbatch production before we try to conduct sampling of color, it is necessary to proofread with the last, but also in this comparison, if the color difference is not, can be considered qualified, as there is a slight color masterbatch batch can be re-used after mixing masterbatch, color masterbatch itself to reduce the mixing caused by uneven. At the same time, we need to focus on testing the thermal stability of the base resin, masterbatch for poor thermal stability, we recommend the manufacturer for replacement.
3. To reduce the impact of temperature on the color of the barrel
Production often encounter due to a heating coil or damage the heating control section burned out of control long dramatic changes in temperature cause the barrel to produce color. Such color is very easy to determine the causes, but generally damage the heating coil will produce color associated with plastics inequality, while heating control section burned out of control long as the product is often accompanied by air spots, discoloration and even severe coking phenomenon. Therefore, the production of heat required to regularly check the section and found the timely replacement of the heating part repair damaged or out of control, in order to reduce the chance of this type of color produced.
4. Elimination of masterbatch masterbatch mixed with the uneven impact
Plastic masterbatch masterbatch mixed with bad products also make color changeable. After the parent materials and masterbatch mechanical mixing, when fed through the lower suction hopper, because the electrostatic interaction, masterbatch masterbatch with separate, easily adsorbed on the hopper wall, which is bound to cause a change in the amount of masterbatch injection cycle, resulting in color. In such cases, the raw material can be taken before the suction hopper to artificial mixing solutions. There are a lot of companies using feeders to join masterbatch, which saves a lot of manpower, and color control to provide a lot of help, but many companies due to improper use, the results are often unsatisfactory. Under the fixed speed feeder join masterbatch plasticizing time depends on the number, and plasticizing time itself is fluctuating, sometimes even relatively large fluctuations, so to ensure a constant feeding quantity, the need to be fixed feeder feeding time and less than the minimum set time plasticizing time. When using the feeder should be noted, because of the smaller feeder outlet, after a period of time, it may be because the screw feeder material accumulated silt caused by cutting allowed, and even cause feeder stall, so need to be cleaned regularly.
5. Reduce the influence of the injection molding process of adjustment
Reasons for non-color injection molding process parameters to be adjusted, as far as possible without changing the injection temperature, back pressure, injection cycle and masterbatch amount, while the need to observe the effect of adjusting the process parameters change color, if found should adjust color. Possible, avoid the use of high injection speed, high back pressure caused by strong shear injection molding process to prevent chromatic aberration due to overheating or thermal decomposition caused by such factors. Strict control barrel temperature of the heating section, in particular close to the nozzle and the heated portion of the nozzle.
6. Master cylinder temperature, the amount of product masterbatch color change
Before color adjustment must also know the product color with temperature, the amount of masterbatch trends. Change the temperature or the amount of masterbatch with different masterbatch production, and its products are different color variation. Which can be determined by trial-color process variation. Unless already know this masterbatch color variation, it is impossible to quickly fine tune color, especially in the new palette when masterbatch production.
