To maintain the quality of optical molded products - The importance of pre-drying and points to note
Optical molded products such as lenses and transparent covers require extremely high quality in terms of appearance and performance. For this reason, "pre-drying" before molding is an essential process. This is because even small amounts of moisture in the resin can cause defects such as cloudiness, silver streaks, and air bubbles.
Dryer selection and molding conditions
Controlling the drying process is extremely important to ensure consistent quality in optical molded products. Insufficient drying can lead to defects such as silver streaks, cloudiness, and air bubbles due to moisture remaining in the resin. On the other hand, excessive drying can lead to thermal degradation of the resin, so proper control of drying temperature and time is essential.
To achieve high-quality drying, we recommend using Dehumidifying Dryer. For Optical in particular, the drying performance of Hot Air Dryer may be insufficient, so we recommend a model that can stably supply dry air with a low dew point. In addition, Air flow rate and air flow inside the drying hopper are also factors in drying the entire resin evenly.
Dried resin easily absorbs moisture when it comes into contact with moisture in the air again. To prevent this, it is necessary to handle the resin with extreme care after drying. The transport route from the dryer to the molding machine should be as sealed as possible to prevent re-absorption of moisture during transport. It is also important to adjust the amount of dried resin supplied to match the molding cycle and to manage the resin so that it is not left standing for long periods of time.
In addition, the quality of optical molded products is greatly affected not only by drying but also by its coordination with molding conditions. If the molding temperature is too high, residual moisture will evaporate too quickly, which can cause silver streaks and bubbles. Optimizing the drying process in conjunction with molding conditions such as injection speed and pressure holding time will help ensure consistent quality.
Features of DMD4
1. Reliability
The drying filter is a heat-resistant resistant, high-performance filter (0.3μm/99.97%) that cleans the heated air at the end. In addition, Matsui's original push damper is used for batch transport, which prevents contamination.
2. Removal of resin powder
Matsui's original Aero Power Hopper transports materials while removing resin powder with airflow.
3. Maintenance
The cyclone separator, which is separated by the weight of the dust, reduces the frequency of cleaning the filter. Maintenance during dry operation is possible by adopting a manual operation butterfly valve.
4. Safety
SSR (contactless relay) for the heater control circuit reduces maintenance frequency and greatly improves safety.
Flow Diagram
