For ultra-thin light Box Light Guide plate, the guide plate has been an unavoidable problem, guide plate ultra-thin lightbox yellowing factors have a variety of, below we together to analyze, a variety of factors under the guide plate yellowing should be how to solve.
The main causes of yellowing of the light guide plate are the following 3
The first: It is the shear heat to the hot runner nozzle head temperature sharply pull, resulting in plastic deterioration yellowing;
Analysis: The yellowing position is near the gate and the position of each mode is fixed.
Solution: This problem is mainly caused by hot runner nozzle at high speed and high pressure, which leads to the high temperature in the gate area, which is the most difficult to solve the problem of yellowing at present. To solve this kind of problem, the main consideration is to consider the cooling problem of the gate area. This kind of problem can be solved by adding water, changing the TOU structure of the nozzle and making the material better for its thermal conductivity.
The second kind: is the runner inside the plastic at high temperature long time to burn the gum
Analysis: Yellowing on the surface of the guide plate and the yellowing position of each mold is dispersed.
Solution: This problem is mainly to see whether there is a dead end in the runner, and there is no problem with the hot runner temperature.
The third: The mold itself due to trapped gas in the injection molding process will be the local temperature in the cavity to pull high cause plastic deterioration.
Analysis: Yellowing position in the corner of the guide plate, and the position is fixed. The main cause of the trapped gas is that the exhaust of the mould itself is not done well. There are three kinds of gas generated in the mould one is the natural air in the mold cavity, the other is the micro-gas that the plastic is not dry enough and decomposes at high temperature; the last one is the mold in the process of using the release agent, washing water, such as the use of unreasonable cause of liquid volatilization of trace gases.
True to the different sources of gas, we usually use the method is to increase the exhaust tank, do overflow trough, reasonable use of release agent to solve.