Super Absorbent Polymer Surface Crosslinking for Urine Diffusion
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Solution Overview
Problem
Existing super absorbent polymers in hygienic materials, such as diapers, face limitations in improving rewet characteristics and leakage suppression despite advancements in design changes, as they do not effectively diffuse urine evenly, leading to potential leakage issues.
Innovation Solution
A super absorbent polymer with a base polymer powder and a surface crosslinked layer formed using a mixture of cyclic alkylene carbonates with specific Hansen solubility parameters, enhancing the polymer's ability to quickly and widely diffuse urine, thereby improving rewet and leakage suppression characteristics while maintaining excellent absorption performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If design changes such as acquisition distribution layer or absorption channel are introduced to improve spreading characteristics, then urine diffusion is improved, but the improvement is insufficient and additional improvements are continuously requested
Solution Approach 1:
The patent applies local quality by creating a surface crosslinked layer with different properties from the base polymer. The surface layer has enhanced crosslinking density and specific Hansen solubility parameters that improve urine diffusion and spreading characteristics locally at the particle surface, while the internal structure maintains high absorption capacity. This resolves the contradiction by optimizing different regions for different functions.
Solution Approach 2:
The patent changes the Hansen solubility parameters of the surface crosslinking agent to achieve optimal urine diffusion. By selecting surface crosslinking agents with specific Hansen solubility parameters (particularly polarity and hydrogen bonding components), the patent optimizes the balance between spreading characteristic and leakage suppression without sacrificing absorption performance.
2Quantity of substance
If surface crosslinking is performed to improve absorption performance, then absorption capacity is enhanced, but spreading characteristic and urine diffusion may be compromised
Solution Approach 1:
The patent segments the polymer structure into two distinct regions: a base polymer region for high absorption capacity and a surface crosslinked layer for improved spreading. This segmentation allows each region to be optimized independently - the base polymer maintains quantity of absorption while the surface layer enhances urine diffusion characteristics.
Solution Approach 2:
The patent creates a composite structure with base polymer powder and surface crosslinked layer formed by surface crosslinking agents. This composite material combines the high absorption capacity of the base polymer with the improved spreading characteristics of the crosslinked surface, resolving the contradiction between absorption quantity and diffusion ease.
3Quantity of substance
If crosslinking density is increased to improve absorption performance, then moisture absorbency is enhanced, but rewet characteristics and leakage suppression may deteriorate
Solution Approach 1:
The patent applies local quality by concentrating crosslinking at the surface layer rather than uniformly throughout the entire polymer structure. The surface crosslinked layer has high crosslinking density for structural integrity and leakage suppression, while the internal base polymer maintains appropriate crosslinking for absorption capacity, preventing rewet issues.
Solution Approach 2:
The patent changes the crosslinking parameters by using specific surface crosslinking agents with controlled Hansen solubility parameters and optimizing crosslinking conditions (temperature, time, agent concentration). This allows precise control of crosslinking density to achieve the right balance between absorption performance and rewet characteristic.
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 effectively diffuses urine across the surface of hygienic materials, significantly enhancing rewet and leakage suppression characteristics while maintaining high absorption and liquid permeability, as demonstrated by improved centrifuge retention capacity and gel bed permeability.
Implementation Method 1
the surface of the super absorbent polymer particles may be crosslinked... allow urine and the like absorbed in the hygiene materials to rapidly and widely diffuse along the surface of the super absorbent polymer particles
Implementation Method 2
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 3
a base polymer powder including a first cross-linked polymer of a water-soluble ethylenically unsaturated monomer having an acidic group of which at least a part is neutralized
Data Source
AI summary
The present invention relates to a super absorbent polymer which not only has excellent basic absorption performance but also can improve rewet characteristics and leakage suppression characteristics of hygienic materials such as diapers, and a method for preparing the same. The super absorbent polymer includes: a base polymer powder including a first cross-linked polymer of a water-soluble ethylenically unsaturated monomer having an acidic group of which at least a part is neutralized; and a surface crosslinked layer that is formed on the base polymer powder and includes a second cross-linked polymer in which the first crosslinked polymer is further crosslinked via a surface crosslinking agent, wherein the surface crosslinking agent includes a mixture of plural kinds of cyclic alkylene carbonates, and where the mixture has a Hansen solubility parameter by hydrogen bonding component of 13 or more.