Currently, diaper pails composite cores are sold on the market. The lower-level SAP collocation mainly adopts three Japanese collocation ratios, that is, the upper level. The lower layers of SAP are in the ratio of 4:6.5:5.6:4, respectively, with great differences in cost, availability and breathability. How to choose the best ratio has positive significance for guiding production. Taking into account the characteristics of the product, SAP with high absorption and high water retention was used as the upper layer of the composite core, and high-pressure high-fluidity SAP was used as the lower layer of the composite core, and three proportions of combined tests were carried out respectively. By comparing the absorption time, drying time, absorption rate and rewet rate, the optimal combination of the upper and lower layers of SAP was discussed, which provided technical support for the selection of the diaper pails.baby pants composite core SAP.
The microstructure of superabsorbent resin will directly affect its water absorption mechanism and water absorption performance. The elastic hydrogel is formed after water absorption, and its water absorption mechanism is different from the traditional liquid diffusion theory.
In terms of thermodynamic theory, when the superabsorbent resin absorbs water, when the normalized degree difference between the resin and the water phase is 0, the water is stable in the resin phase, so the water penetrates into the resin until equilibrium. Resin absorbs water mainly because it is prone to hydrogen bonding. This tendency is greater if there are polar ionic groups. If limited to an appropriate negative value, the swelling of water in the superabsorbent resin is limited. For linear polymers, the crystalline domains play the role of limiting water swelling through physical cross-linking. However, most superabsorbent resins are cross-linked by chemical bonds, mainly covalent bonds or ionic bonds. The salt-resistant water-absorbent resin also absorbs water by the dynamic force generated by the osmotic pressure, but the ions formed by the ionization of the salt in the water will reduce the osmotic pressure, thereby reducing its water-absorbing capacity. When absorbing salt water, since the ionic strength of salt is much greater than that of fresh water, the water absorption capacity will also be significantly reduced. At this time, the nonionic hydrophilic functional groups in the salt water absorbent resin will form hydrogen bonds with water molecules, thereby absorbing water.
The absorption rate is mainly affected by the SAP content of the composite core. When the SAP content of the composite core remains unchanged, the performance characteristics of the upper and lower layers of the core SAP directly affect the absorption rate. As the ratio of high absorption and high pressure SAP increases, the absorption rate increases. When high absorption SAP is used together with liquid SAP, the absorption capacity of the core can be fully exerted.
On request, the rewet volume of Infant diaper pails is ≤ 10g. The samples were subjected to 3 times of 60ml pressure test solution infiltration test, and the amount of re-infiltration was tested, and 3 tests were carried out for 3 groups of samples. The rewet amount of the first and second groups of samples exceeded 10g and could not keep the surface of diaper pails dry.
The rewet performance test found that the rewet amount of the third group of samples was very small, and the third pressure rewet amount was much lower than that of the other two groups of samples. When 180 ml of the test solution was poured three times, the amount of rewet was only 8.2 g. Under the strict standard test conditions, the rewet amount can also meet the standard requirements. It shows that the third group of combination has the functions of rapid, multiple absorption and conduction of liquid, and can also effectively prevent liquid from re-seeding, so that the sample can better keep the surface of diaper pails dry, breathable and comfortable. In terms of consumer comfort, the third group has a clear advantage.
When the ratio of diaper pails.baby pants high-absorption and high-water-retention SAP to high-pressure high-pass liquid SAP is 6:4, the advantages of the two materials are fully complemented, which can not only give full play to the high absorbency of SAP, but also reflect its high-pass liquid property. At the same time, according to the current market price, the high absorption and high water retention SAP is relatively cheap, and the cost of the two SAP is reduced by 6:4.