Customers used TPE and TPR materials before, but the products they made recently are prone to cracks. The composite sucker uses two kinds of soft and hard TPE materials to bond together. The higher hardness part is no problem, and the lower hardness (about 10A) part has many small cracks (cracks) on the surface.
Analyze the samples, one is the weather, and the other is the product cracks caused by insufficient material strength. The detailed analysis is as follows:
one. weather reason
When the temperature is low, the molecular arrangement of the microstructure of the TPE material (rubber phase) will change, and the relative slippage of the molecules will become difficult, or the tensile properties will become poor. During the use of the suction cup, the TPE parts with lower hardness will be stretched under the action of external force. However, due to the low temperature, the stretchability will become worse and exceed the limit of the material, which will cause the product to break (crack).
二. Material strength
The problem of tensile performance mentioned above is that the product cracks due to the decrease of the material's low temperature resistance to tensile deformation. If a matrix material that can maintain tensile properties at low temperatures can be used, this problem will be solved.
To sum up, the sucker product appears to be cracked, the external cause is the cold weather, and the internal cause is the change in the molecular arrangement of the material, and the stretchability is deteriorated. The combined effect of external and internal factors caused cracks in the TPE suction cup.
The above is just a case of cracks in sucker products to analyze the causes of cracks in TPE/TPR products. In fact, there are other reasons for cracks in TPE/TPR products, which should be analyzed in detail according to the material characteristics and actual processing conditions:
1. The TPR of the SBS substrate has poor aging resistance and is prone to aging cracks;
Solution: It is recommended to change to SEBS substrate TPE.
2. TPR shoe material with SBS base material, if there are cracks (cracks) during the glue brushing process, it may be caused by glue corrosion;
Solution: It should be noted that the glue should not be brushed too much and should not be condensed together.
3. Some TPE products with low hardness and thicker dimensions may suffer from stress shrinkage due to insufficient pressure holding during the injection molding process, and cracks may occur in severe cases.
Solution: Strengthen the molding pressure to eliminate stress shrinkage.