Super Absorbent Polymer Permeability via Core-Shell Mixing
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Solution Overview
Problem
Existing methods for improving the permeability of super absorbent polymers, such as adding silica or clay during surface crosslinking, result in decreased water holding capacity and absorption power under pressure, and are prone to separation due to external physical impacts.
Innovation Solution
A method involving thermal or photopolymerization of a monomer composition to form a hydrogel polymer, followed by drying, pulverization, and mixing with a surface crosslinking agent and polymer particles having a core-shell structure, where the glass transition temperature of the core is lower than that of the shell, under conditions below the shell's glass transition temperature, to enhance permeability without compromising water holding capacity or absorption power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silica or clay is added during surface crosslinking to improve permeability, then permeability is improved, but water holding capacity and absorption power under pressure decrease
Solution Approach 1:
The invention changes the physical and chemical parameters of the super absorbent polymer by controlling the glass transition temperature difference between core and shell polymers, and by controlling the mixing temperature below the shell's Tg, to achieve improved permeability while maintaining water holding capacity
Solution Approach 2:
The invention creates a composite structure with core-shell polymer particles where the core provides flexibility (lower Tg) and the shell provides structural integrity (higher Tg), forming a composite material that simultaneously achieves improved permeability and maintained absorption properties
2Reliability
If silica or clay is added during surface crosslinking to improve permeability, then permeability is improved, but the material becomes prone to separation under external physical impact
Solution Approach 1:
The invention changes the glass transition temperature parameters of the polymer components, ensuring the core polymer has lower Tg than the shell polymer, and controls the mixing temperature below the shell's Tg to optimize the balance between permeability and mechanical strength
Solution Approach 2:
The core-shell composite structure provides both improved permeability through the core's flexible matrix and enhanced resistance to separation through the shell's stronger structure, eliminating the need for silica or clay additives
3Reliability
If the glass transition temperature of the shell polymer is lowered to improve permeability, then permeability improves, but water holding capacity decreases
Solution Approach 1:
The invention applies different glass transition temperature characteristics to different parts of the composite structure: the core polymer has lower Tg to provide permeability, while the shell polymer has higher Tg to maintain water holding capacity and structural integrity
Solution Approach 2:
By creating a composite of two polymers with different Tg values in core-shell configuration, the invention achieves local optimization where each component performs its specific function without compromising the other
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 method achieves improved permeability of super absorbent polymers while maintaining or enhancing water holding capacity and absorption power under pressure, with uniform distribution of polymer particles on the surface preventing agglomeration and ensuring strong physical bonding, thus minimizing separation during movement.
Implementation Method 1
carrying out a thermal polymerization or a photopolymerization of a monomer composition including a water-soluble ethylene-based unsaturated monomer and a polymerization initiator to form a hydrogel polymer
Implementation Method 2
carrying out a thermal polymerization or a photopolymerization of a monomer composition including a water-soluble ethylene-based unsaturated monomer and a polymerization initiator to form a hydrogel polymer
Implementation Method 3
in the polymer particle having the core-shell structure, a glass transition temperature (Tg) of a polymer forming a core portion is lower than a glass transition temperature (Tg) of a polymer forming a shell portion, and wherein the step of mixing the pulverized polymer with the surface crosslinking agent and the polymer particle having the core-shell structure is carried out under conditions where a temperature of the pulverized polymer and the surface crosslinking agent is lower than a glass transition temperature (Tg) of a polymer forming a shell portion of the polymer particle
Data Source
AI summary
The present invention relates to a method for preparing a super absorbent polymer. The method for preparing a super absorbent polymer according to the present invention comprises the steps of: preparing a hydrogel polymer by carrying out a thermal polymerization or a photopolymerization of a monomer composition including a water-soluble ethylene-based unsaturated monomer and a polymerization initiator; drying the hydrogel polymer; pulverizing the dried polymer; mixing the pulverized polymer with a surface crosslinking agent and a polymer particle having a core-shell structure; and carrying out a surface crosslinking reaction. According to the present invention, the super absorbent polymer having improved permeability can be obtained by adding the polymer particle during surface crosslinking.