Water retention for SAP of International brand diapers


As we know, SAP (super absorbent polymer) as "engine" of diapers , largely determines the merits of diaper performance. There are several indicators to measure SAP performance: retention ratio of water absorption,rate of absorption, absorption amount of pressure, liquid permeability, particle size.


Although more and more composite core diapers are emerged in domestic market, but the performance is hardly exceeding these international brands like Merries, Pampers. Today let’s analyze the SAP water retention performance used in diapers for those international brands.


We chose the Japanese Merries, Moony, American Pampers, Germany Eress. These four brands passed the standard test method, the performance is better followed by Merries, Eress, Pampers, Moony. We use the professional technology to separate the absorbent polymers from the diapers, then tested the saturation absorption and water retention rate under 0.9% physiological saline, the test results are as follows:



In these four diapers, only Moony SAP water retention rate slightly higher than 30g/g, the other three are low-water retention SAP. Then how about each brand liquid permeability and other index? Why would they choose this low water-retention polymer? The following chart show us these four diapers in the SAP liquid permeability.


Many people considered as the SAP's water absorption rate is more higher more better, but they don’t know that it’s a  complicated relationship among these indexes of the SAP, it’s appears like complementary and interacting relationship. Such as the water retention and absorption rate with the liquid permeability. Generally speaking, if the water retention and absorption rate of SAP is high , the liquid permeability will be either normal or sometimes even worse; On the contrary, if the liquid permeability is better, the water retention and absorption rate will not be too high.

Now many diaper’s manufacturers considered the SAP pressure absorption as an important index, it has a certain relevance with the liquid permeability. The following chart shows the SAP pressure absorption of those four diapers.


For high-end diapers, people usually change the diapers after baby peeing 2 or 3 times, urine volume on average is less than 150 ml. That required the rapid transmission capacity of SAP , high liquid permeability and high pressure SAP is coming into being: the urine quickly absorbed and conducted will help the diaper dry. Good diapers are not only in big absorbency, the more important is absorbent and dry quickly.


Therefore, a large number of experimental data show that the superior performance of diapers is not only determined by the high absorbency SAP, but keeping about 30 water retention capacity, in the meanwhile increase the liquid permeability and SAP pressure absorption. In order to ensure that urine  conduct quickly in SAP and lock the moisture in the urine.