Superabsorbent Polymer Surface Crosslinking for Rapid Absorption
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Solution Overview
Problem
Existing methods for enhancing the absorption speed of superabsorbent polymers in hygienic goods, such as diapers, often require the use of blowing agents and surfactants, which can degrade the polymer's properties and increase fines during processing.
Innovation Solution
A superabsorbent polymer composition is developed that includes a base resin with crosslinked acrylic acid-based monomers and an internal crosslinking agent, along with a surface crosslink layer formed using a surface crosslinking agent comprising carbonate and diol-based compounds, eliminating the need for blowing agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a blowing agent is used to form a porous structure inside the superabsorbent polymer, then the absorption speed is improved, but the strength of the superabsorbent polymer decreases and fines are generated in large quantities
Solution Approach 1:
The patent removes the blowing agent from the system entirely, replacing it with a surface crosslinking agent that forms a porous structure on the surface without compromising the internal strength of the polymer particles. This extraction of the harmful element (blowing agent) while maintaining the beneficial function (porosity for absorption) resolves the contradiction between absorption speed and strength.
Solution Approach 2:
The invention applies crosslinking locally on the surface of the polymer particles rather than throughout the entire particle structure. The surface crosslink layer with controlled porosity provides rapid absorption pathways while the uncrosslinked or less crosslinked interior maintains structural integrity and strength, thus resolving the contradiction between surface absorption speed and overall particle strength.
2Speed
If excessive amount of blowing agent and surfactant is used to improve absorption speed, then the absorption speed increases, but the properties of superabsorbent polymer such as surface tension, permeability and bulk density are deteriorated
Solution Approach 1:
The patent extracts and eliminates the blowing agent and excessive surfactant from the formulation, replacing them with a surface crosslinking agent that provides the necessary porosity and absorption speed improvements without deteriorating the polymer's surface tension, permeability, and bulk density properties.
Solution Approach 2:
The invention changes the approach from using chemical additives (blowing agents and surfactants) to control porosity to using a surface crosslinking process with specific crosslinking agents. This parameter change in the method of creating porosity allows for improved absorption speed while maintaining reliable polymer properties.
3Area of stationary object
If blowing agent is used during polymerization to form pores, then the surface area is broadened, but productivity deteriorates due to fines generation during drying and grinding
Solution Approach 1:
The patent removes the blowing agent from the polymerization process and instead applies surface crosslinking after polymerization to create the porous structure. This eliminates the generation of fines during drying and grinding that occurs when pores are formed during polymerization, thereby maintaining productivity while still achieving the necessary surface area for rapid absorption.
Solution Approach 2:
The surface crosslinking process is applied as a preliminary or post-polymerization treatment to create the porous surface structure before the drying and grinding steps. This preliminary formation of surface porosity without internal blowing agents prevents fine particle generation during subsequent processing, maintaining productivity.
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 solution achieves rapid absorption speed without compromising the polymer's bulk density, surface tension, permeability, or increasing fines, thereby improving the efficiency and productivity of the superabsorbent polymer production process.
Implementation Method 1
a surface crosslink layer formed on the surface of the base resin, in which the crosslinked polymer is additionally crosslinked by a surface crosslinking agent
Implementation Method 2
superabsorbent polymer comprising a base resin comprising crosslinked polymer of acrylic acid based monomers
Data Source
AI summary
This invention relates to a superabsorbent polymer composition and a method for preparing the superabsorbent polymer composition. According to the present disclosure, there are provided a superabsorbent polymer composition that can exhibit a rapid absorption time without using a blowing agent, and a method for preparing the superabsorbent polymer composition.