The product discolors and becomes brittle after ultraviolet irradiation

During the rotational molding production process, the product exhibits the quality defect of 「The product discolors and becomes brittle after ultraviolet irradiation」. The specific manifestation is that the product turns yellow and brittle after outdoor use. This defect is relatively common when processing materials such as powders such as LLDPE, HDPE, PVC, PA, and its occurrence conditions are usually related to unreasonable settings of heating temperature and time, rotation speed ratio, cooling rate, mold wall thickness. When the The product discolors and becomes brittle after ultraviolet irradiation situation is severe, it causes a series of cascading quality defects in the product in terms of appearance, dimensional accuracy, mechanical properties, and other aspects, not only reducing the product's functionality and safety in use, but also directly increasing the scrap rate and production costs. Therefore, this problem requires systematic diagnosis and optimization from multiple dimensions, including material selection, rotational molding machine, heating oven, rotating arm, cooling station condition, and heating temperature and time, rotation speed ratio, cooling rate, mold wall thickness.

1. Poor UV resistance of the resin. The selection and handling of materials is the foundation of molding quality. The intrinsic characteristics of the resin, such as molecular weight, molecular weight distribution, and melt index, determine its processing window and final performance. Factors such as excessive moisture content of raw materials, mixing of impurities, and improper proportion of recycled material can all cause various defects during processing. 2. No light stabilizer added. This factor leading to the problem reflects that certain process conditions or material characteristics in rotational '2079851475616104453ing do not meet the optimal molding requirements. Such problems are often cumulative and concealed, and should be investigated and verified as key focus items during process debugging and finalization to ensure that hidden dangers are eliminated at the source. In addition, the insufficient overall coordination between powder melting uniformity and product wall thickness control is also a factor that cannot be ignored. There are complex interactions and coupling relationships among the process parameters, and the deviation of any parameter may aggravate the degree of The product discolors and becomes brittle after ultraviolet irradiation through chain effects. In terms of equipment maintenance, the regular overhaul and precision confirmation of the rotational molding machine, heating oven, rotating arm, and cooling station are not in place, causing the actual operating parameters of the equipment to deviate from process requirements, which can also become a potential inducement of the The product discolors and becomes brittle after ultraviolet irradiation problem.

1. Add UV absorbers and light stabilizers. Adjustments to the formulation and ratio should be determined on the basis of laboratory small-scale tests, and then verified by online pilot tests. Any change to the formulation should be recorded and evaluated for its full impact on product performance. Automatic metering and batching devices can effectively reduce errors and batch-to-batch fluctuations of manual batching. 2. Select weather-resistant resin. Before introducing new tools, new materials, or new methods, sufficient applicability evaluation and small-batch verification should be carried out. It is recommended to first conduct offline tests or simulation analysis outside production conditions, and introduce them into the formal production line only after confirming effectiveness and safety. Keep change management records for subsequent traceability and experience accumulation. 3. Apply surface coating protection. Protective treatment of equipment and molds can effectively extend service life and maintain precision. Exposed precision surfaces should be coated with anti-rust oil, and molds not used for a long time should be sealed for storage. Add anti-rust and anti-corrosion agents to cooling water, and install filters on pipelines. Good protection habits can reduce unplanned downtime and lower maintenance costs. In terms of material management, incoming inspection of raw materials and in-process inspection of work-in-progress should be strengthened, and the key performance indicators of powders such as LLDPE, HDPE, PVC, PA should be strictly controlled to ensure the stability of molding quality from the source.

In summary, the causes of the 「The product discolors and becomes brittle after ultraviolet irradiation」 problem can be attributed to the combined action of multiple factors such as poor UV resistance of the resin and no light stabilizer added. Solving this problem requires starting from aspects such as adding UV absorbers and light stabilizers and selecting weather-resistant resin, and adopting systematic governance measures. In actual production, it is recommended to establish a prevention and rapid response mechanism for this problem, and achieve stable production and continuous improvement through powder melting uniformity and product wall thickness control.