TPE｜There is a deviation between the hardness of the finished TPR injection molding product and the hardness of the raw material?
Time of issue:2023-04-15
The problem as described in the title is not reasonably likely to occur. The same material, whether raw or processed into products, the hardness must not change. For the hardness is soft? Estimated that there are the following two factors.
1 do the product is thin, such as 1mm and below
For example, the same 90 degrees of TPE, particle diameter in 3mm or so. Pinch up more hard, will not happen rebound or deformation. But if made into 1mm or thinner sheet, it is easy to bend deformation. It feels like the finished product is much softer than the granular raw material, but in fact the hardness is the same.
2. The product has not been cooled
The product has just been molded out, not yet completely cooled and shaped. At this time, by hand and test, will be a little soft (generally soft 5 ~ 10 degrees). After 24 hours of cooling, the test hardness is normal.
Therefore, in testing the hardness of TPE materials, the thickness of the test piece has a greater impact on the accuracy of the material hardness test, generally with a value of about 6.35mm as the standard test thickness of the test piece. The thickness of the test piece is too thin, the test hardness is high, the thickness is thick, the test hardness is low.
In addition, the same formula of a TPE, TPR material, winter than summer hardness will be softer (about 5 degrees), which is also due to the influence of temperature.
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