Super Absorbent Polymer With Differentiated Crosslinking
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Solution Overview
Problem
Existing super absorbent polymers used in hygiene materials like diapers and sanitary napkins face challenges in maintaining high absorption rates and elasticity under pressure, leading to rewetting and urine leakage issues.
Innovation Solution
A super absorbent polymer with a recovery rate of 85% or more, achieved through a specific polymerization process involving an acrylic acid-based monomer, foaming agent, internal crosslinking agent, and surface crosslinking, which maintains elasticity and absorption performance even under pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the degree of internal crosslinking is lowered and the degree of surface crosslinking is increased to improve absorption rate, then the absorption rate increases, but liquid remains on the surface after swelling causing decreased wearing feeling and skin rash
Solution Approach 1:
The patent applies different crosslinking degrees to different parts of the super absorbent polymer particle - lower internal crosslinking (0.01-0.5 mmol/g) for rapid liquid uptake and higher surface crosslinking (0.1-1.0 mmol/g) for liquid retention. This local differentiation of structural properties resolves the contradiction between fast absorption and surface dryness.
Solution Approach 2:
The patent optimizes specific parameter ranges for internal and surface crosslinking degrees to achieve the desired balance. By controlling internal crosslinking at 0.01-0.5 mmol/g and surface crosslinking at 0.1-1.0 mmol/g, the polymer achieves both rapid absorption and surface dryness, preventing the harmful effect of liquid remaining on the surface.
2Ease of operation
If pressure is applied to the super absorbent polymer after it absorbs liquid, then the polymer is compressed, but liquid leaks out causing rewetting and urine leakage
Solution Approach 1:
The enhanced surface crosslinking creates a stronger outer shell that resists compression-induced liquid leakage. The surface crosslinked layer acts as a protective barrier that maintains structural integrity under pressure, preventing the harmful effect of liquid leakage while allowing the internal structure to maintain absorption capacity.
Solution Approach 2:
The super absorbent polymer forms a composite structure with differentiated crosslinking zones - a loosely crosslinked internal core for absorption and a densely crosslinked surface layer for mechanical strength and liquid retention under pressure. This composite architecture prevents rewetting and urine leakage.
3Strength
If the super absorbent polymer absorbs liquid and is then pressed multiple times, then compression is applied, but the polymer loses elasticity and recovery performance
Solution Approach 1:
The optimized crosslinking parameters create a balanced network structure that maintains elasticity. The internal crosslinking density of 0.01-0.5 mmol/g provides sufficient structural support while allowing chain mobility for recovery, achieving high recovery rates even after repeated compression cycles.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The polymer exhibits rapid absorption rates and excellent dryness characteristics, preventing rewetting and urine leakage, while maintaining physical properties like gel strength and resilience.
Implementation Method 1
Super absorbent polymer (SAP) is a synthetic polymer material capable of absorbing moisture from about 500 to about 1,000 times its own weight
Implementation Method 2
polymerizing a monomer composition including an acrylic acid-based monomer having at least partially neutralized acidic groups to form a hydrogel polymer
Implementation Method 3
a method of lowering the degree of internal crosslinking and increasing the degree of surface crosslinking
Data Source
AI summary
The present disclosure relates to: a super absorbent polymer having a rapid absorption rate and maintaining elasticity even in a condition of being pressed multiple times, thereby having excellent dryness characteristic; and a preparation method therefor. The super absorbent polymer of the present disclosure exhibits excellent performance for use in hygiene materials such as diapers.