This core design is primarily found in disposable hygiene articles produced and used in China. Compound cores do not use cellulose fluff. Instead, they are made by “sprinkling” superabsorbent polymer (SAP) on a layer of high loft nonwoven and enclosing this composite with a top and bottom layer core wrap made of tissue or nonwoven. With this process, the SAP particles are entangled within the synthetic nonwoven fibers. A core adhesive is necessary to maintain the three layers and to keep the SAP particles contained within the core material.
Compound cores are often constructed offline and transported in boxes or rolls to the hygiene production line. In order to include them into a diaper, the compound cores are fed onto the diaper production line and encased in the core wrap. A core adhesive may be necessary to position the core material and maintain it within the different layers of the core system. Recently, there is an increase in machinery that can produce these cores online.
The synthetic nonwoven fibers used in compound cores have poor wicking abilities. When manufactured offline, the compound core also needs to be manipulated several times before being integrated into a diaper, meaning SAP loss is greater due to shaking. Using the right core adhesive can help reduce SAP loss while also impacting wicking and improving core integrity.
While the concept of using synthetic nonwoven fibers instead of cellulose fluff may simplify the supply chain, compound cores can be expensive to make as they may require slower line speeds for production.