Development Trends of Laminated Core Materials for Disposable Diapers

1. Performance Optimization: Integrating Ultra-Thinness, High Absorbency, and Leakage Prevention

• Ultra-thinning as a core competitive edge: Traditional laminated cores are relatively thick due to the use of fluff pulp. The industry now achieves ultra-thinness by improving the unit water absorption efficiency of super absorbent polymers (SAP) and optimizing the compression ratio of core structures. Leading products have reduced core thickness from 3.2mm in 2019 to less than 1.8mm, with some five-layer laminated (SAP Sheet) cores as thin as 2.48mm. Ultra-thin cores (≤1.8mm) are expected to become the standard for high-end products in the future. Technologies such as gas-phase SAP preparation and fiber length optimization ensure no clumping or splitting while maintaining ultra-thinness.

• Synergistic improvement of absorption and leakage prevention: The ratio of SAP to fluff pulp is optimized (e.g., 65%-35% resin-fluff pulp ratio) to balance absorption efficiency and cost. Structural innovations like 3D diversion channels and layered SAP distribution enable rapid liquid diffusion and secure water locking, addressing key user pain points.

2. Material Innovation: Bio-Based Materials Leading the Eco-Friendly Transformation

• Gradual replacement of petroleum-based materials: Guided by global carbon neutrality policies, biodegradable bio-based materials have become a critical transformation focus. Commercialized technologies include corn starch-acrylic acid copolymer SAP and sugarcane bagasse fiber-sodium alginate laminated cores. Corn starch-based SAP achieves ≥90% soil degradation within 180 days. Although current bio-based material costs are 2.3-2.8 times higher than petroleum-based alternatives, process optimization and large-scale production are expected to drive significant cost reductions by 2028, with high-end market penetration rising from less than 5% to 20%.

• Exploration of fluff pulp substitutes: Traditional fluff pulp aids liquid diversion and storage but increases core thickness and environmental impact. The industry is actively developing alternatives such as cotton fiber and plant fiber. For example, Babycare uses a surface layer blended with 30% cotton fiber paired with a new-type core to maintain diversion performance while reducing environmental burden. Future fluff pulp-free cores will compensate for insufficient liquid storage with high-quantity diversion layers, expanding their application scope.

3. Refined Structural Design: Adapting to Advanced Molding Processes

• Layered and modular design as mainstream: To solve uneven liquid distribution and local leakage, laminated cores are shifting from single mixed structures to layered modular designs. For instance, Kera Co., Ltd.’s laminated core consists of sequentially stacked infiltration layers, polymer layers, and diversion layers, each with specific functions. Layered cotton core designs—with less SAP in the upper layer and more in the lower layer—targetedly enhance water-locking capacity. Mesh structure designs further improve core strength, preventing breakage and clumping after absorption.

• Maturation of fluff pulp-free processes: The fluff pulp-free "sandwich" layered structure is gaining traction for its ultra-thinness and simplified production. Currently, SAP ratios in cores reach 50%-70% in Western Europe and North America, with domestic manufacturers following suit. Future optimizations to diversion layer design and SAP colloid strength will address the low liquid storage capacity of fluff pulp-free cores, promoting large-scale application. Molding processes suitable for high SAP content, such as H-shaped and U-shaped molding, will become more prevalent.

4. Localized Supply Chains: Enhancing Collaboration, Cost Reduction, and Self-Reliance

           Previously, core materials like high-end SAP and specialized non-woven fabrics relied heavily on imports. Today, domestic enterprises are shifting from individual material breakthroughs to full-link integration. Wanhua Chemical not only supplies SAP but also establishes joint laboratories with downstream brands; Jinsanfa extends vertically to finished product manufacturing, offering an integrated "non-woven fabric + disposable diaper" solution. Domestic non-woven fabrics have made strides in skin-friendliness and adaptability—for example, Babycare’s plant-derived skin-friendly surface layer (developed with partners) reduces costs by 18% while outperforming international competitors. Over the next five years, domestic materials are expected to achieve over 60% localization in mid-to-high-end laminated cores, significantly reducing the industry’s reliance on international giants.

5. Scenario-Specific Customization: Meeting Diverse User Needs

           Laminated cores are moving beyond one-size-fits-all designs toward refined customization for different populations and scenarios. For active infants, cores prioritize dynamic leakage prevention and soft skin-friendliness, paired with elastic fitting structures to adapt to crawling and turning. For adult Diapers targeting disabled elderly and post-surgical patients, five-layer laminated cores balance high absorption capacity and ultra-thin discretion. The high-end maternal and infant market focuses on weakly acidic, low-irritation core combinations—such as skin-friendly core sets with a stable pH of 5.2-5.8—to align with the natural acid mantle of infant skin, minimizing irritation.