New Development Of Absorbent Material Used In Diapers

1. Development of absorbent material used in diapers

This article presents new developments in absorbent material used in diapers.

Super Absorbent Polymers (SAP) are synthetic polymers primarily used as water-absorbing materials due to their unique property of absorbing large amounts of water relative to their mass.

Typically, SAP gel particles with a high CRC in diapers are easily collapsed and deformed under pressure, losing the fluid permeability required to function. In order to improve the fluid permeability to the expected value, a common method is to reduce the CRC to a lower level, and the AUP is also improved to a certain extent while the fluid permeability is improved.

2. Liquid permeability

Recently, a SAP with high fluidity, medium CRC and high AUP, SAP-HP, was developed. Through proper process, SAP particles can achieve a good balance of internal and external crosslinking, improve their liquid permeability, and meet the needs of diapers. The company determined the fluid permeability of this new SAP using industry-accepted methods and a standard GBP instrument.

Through SAP-HP and other SAP liquid permeability test experiments of other suppliers on the market, the amount of liquid that passes through the gel layer within 2 minutes is recorded, and the amount of liquid has a linear relationship with time. The line representing SAP-HP has the greatest slope, which indicates the fastest flow rate. The liquid flow rate through the material is the main factor determining the liquid permeability, and it is a very important indicator in the application of diapers. Higher liquid permeability indicates higher liquid flow rate, which is more important for diapers with reduced fluff pulp content and increased SAP content. By calculating the liquid flow rate of different SAP gel layers, the liquid flow rate is the fastest in SAP-HP. During the tests performed on the SAP-HP, it was observed that the liquid continued to flow unimpeded from the entire area of the bottom of the instrument for a period of 3 minutes (the time required to complete the test). For the other 3 SAPs, the fluid flow rate was slower and relatively blocked.

Then calculate the liquid permeability GBP value. When the bottom area of the device is constant, the change in height represents the volume change of the material. As the SAP absorbs water, the volume expands continuously, forming a stable gel layer, and the liquid permeability also increases. Therefore, to some extent, it can be said that the greater the AUP under pressure and the larger the volume of gel particles after liquid absorption, the better the liquid permeability of SAP. The GBP value of SAP-HP is the highest, which is about 35% higher than the SAP of Supplier A, which ranks second, while the GBP values of the other two SAPs are lower. The high GBP value of SAP-HP indicates that liquid can pass through the gel layer easily and quickly without any gel blocking when it is used in diapers. In cores using high-pass liquid SAP, liquid can flow through the gaps between SAP particles.

3. Centrifuge water retention

Generally, as CRC increases, the fluid permeability of SAP decreases. Most of the SAPs with high CRC on the market have low or no permeability, while other SAPs with medium CRC values have rather low permeability. SAP-HP has a good balance of fluid permeability, CRC and AUP. The liquid permeability of SAP-HP and its CRC value show the stability of its gel particles, and this property is obtained by proper internal and surface crosslinking. This type of SAP is very suitable for improving the performance of diapers, such as absorption speed, anti-reverse seepage and anti-leakage, etc. By comparing the liquid permeability GBP value and pressure absorption AUP of different SAPs, it can be found that SAP-HP has better comprehensive properties, and at the same time has high liquid permeability and higher AUP value, which once again proves that it is more suitable for improving diapers performance. By briefly introducing the new development of absorbent material used in diapers, it is expected to provide a reference for the research of this industry.