Reasons for Cracking and Cracking of TPR Raw Material Products
Source：德创化工Time：2020-05-25Hits：2351
TPR material for adult products, soft toys, simulation of arts and crafts products, injection molded with cold air blowing, or left for a few days, products prone to cracking or cracking phenomenon
Cracks (cracks) can be divided into two types: aging cracks and stress cracks. The following are brief analysis of the causes and solutions.
1. Aging and cracking
Cause analysis: TPE and TPR compounds are not good enough in aging resistance, and TPE,TPR of SBS system is easy to be aged. In addition, the quality of operating oil will also affect the aging resistance of TPE and TPR compounds (according to the analysis of senior people in the industry, high hydrogenation degree of operating oil will result in better aging resistance of materials).
Countermeasures: SEBS substrate is adopted; Oil with high hydrogenation degree is adopted; The blending system is added with antioxidant.
2. Stress cracking
Cause analysis: polymer materials will produce stress orientation along the flow direction when in molten state. The faster the flow rate is, the more obvious the molecular orientation effect is. Molecules will produce orientation stress when orientation occurs. If the injection or extrusion products are not properly processed, the stress in the products may not be completely eliminated, and the surface stress effect of the products is more obvious, which will lead to cracking or cracking of the products when serious.
Countermeasures:
The injection molded product is subjected to pressure maintaining treatment, and the product is taken out after the mold is opened after stress is eliminated; Annealing treatment: short heat treatment is carried out on products by spark spray gun or (hot air blowing) to eliminate residual stress and reduce and eliminate stress cracking (cracks). Some thicker soft TPE products are more prone to stress cracking.
Generally speaking, stress cracking occurs within half an hour to a few days after the product is processed, while aging cracking occurs within a few days to a month.
