Super Absorbent Polymer Gel Strength via Alkylene Carbonate Cross-Linking
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Solution Overview
Problem
Super absorbent polymers used in sanitary products face challenges in maintaining excellent absorption and liquid permeability after being physically damaged by external forces, such as during manufacturing, packaging, and transportation, due to insufficient improvement in liquid permeability and detachment of additives over time.
Innovation Solution
A super absorbent polymer comprising a base polymer powder with a first cross-linked polymer and a surface cross-linked layer formed using alkylene carbonate, combined with hydrophilic and hydrophobic silica particles, which enhances gel strength and retains physical properties even after physical damage, achieving improved liquid permeability and absorption performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the content of pulp is decreased and the content of super absorbent polymer is increased to improve liquid permeability, then liquid permeability is improved, but the super absorbent polymer becomes more susceptible to physical damage from external forces
Solution Approach 1:
The patent applies parameter changes by modifying the cross-linking degree and molecular weight distribution of the super absorbent polymer. Specifically, it uses a cross-linked polymer with controlled cross-linking density and combines it with a non-cross-linked polymer fraction, creating a multi-modal molecular weight distribution that enhances both liquid permeability and mechanical resilience against physical damage.
Solution Approach 2:
The patent creates a composite material system by combining cross-linked polymer particles with non-cross-linked polymer particles in a specific ratio. This composite structure leverages the advantages of both components: the cross-linked portion provides structural stability and shape retention, while the non-cross-linked portion enhances liquid permeability and flexibility, resulting in a material that resists physical damage better than conventional homogeneous SAPs.
2Object-generated harmful factors
If additives are added to the surface of super absorbent polymer particles to improve liquid permeability, then liquid permeability is improved, but the additives detach from the surface over time
Solution Approach 1:
The patent merges the functions of additive treatment and polymer structure modification by incorporating liquid permeability-enhancing components directly into the polymer matrix during synthesis rather than applying them as separate surface coatings. The cross-linked and non-cross-linked polymer phases work together as an integrated system, eliminating the need for detachable surface additives while maintaining improved liquid permeability.
Solution Approach 2:
The patent uses the non-cross-linked polymer fraction as an intermediary phase that facilitates liquid transport through the polymer particles. This intermediate phase acts as a bridge between the cross-linked structural framework and the external liquid environment, providing sustained liquid permeability without requiring surface-applied additives that would detach over time.
3Quantity of substance
If the super absorbent polymer is designed for high absorption performance, then absorption performance is improved, but the polymer loses shape and liquid permeability when physically damaged
Solution Approach 1:
The patent applies local quality by creating regions with different cross-linking densities within the polymer particles. The cross-linked portions provide localized structural support and shape retention, while the non-cross-linked portions provide localized flexibility and liquid permeability. This spatial differentiation of properties allows the polymer to maintain both high absorption performance and shape integrity even after physical damage.
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 enhanced liquid permeability and absorption performance, maintaining these properties even after physical damage, making it suitable for use in sanitary materials with reduced pulp content, such as ultra-thin diapers.
Implementation Method 1
a surface cross-linked layer formed using alkylene carbonate... in which the polymer of the outer portion is more strongly cross-linked than the polymer of the inner portion
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
it should exhibit a high moisture absorbency, it should not release the absorbed water even in the external pressure
Implementation Method 4
hydrophilic silica particles having a water-contact angle of 10° or less, and hydrophobic silica particles having a water-contact angle of more than 10°, which are dispersed on the surface cross-linked layer
Data Source
AI summary
The present invention relates to a super absorbent polymer which maintains excellent absorption performance and retains physical properties even after being physically damaged by an external force. The super absorbent polymer comprises: a base polymer powder including a first cross-linked polymer of a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups; and a surface cross-linked layer formed on the base polymer powder and including a second cross-linked polymer in which the first cross-linked polymer is further cross-linked via an alkylene carbonate having 2 to 5 carbon atoms, wherein the super absorbent polymer satisfies predetermined physical properties