Polyacrylic Acid Resin Production Reducing Residual Monomers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing polyacrylic acid (salt)-based water absorbent resins face challenges in reducing residual monomers, leading to increased costs, safety concerns, and decreased water absorption performance due to the use of additives, which also cause coloration and foul odors.
Innovation Solution
A method involving polymerization of an aqueous monomer solution with an iron content of 2 ppm or less, followed by surface crosslinking and storage for 3 days or more, with a moisture content of 1% or more, and inclusion of aggregation and coloration preventing agents, results in a resin with reduced residual monomers and improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additives are used to reduce residual monomers, then the amount of residual monomers is reduced, but cost increases and water absorption performance decreases
Solution Approach 1:
The patent removes additives from the polymerization system entirely, using instead controlled polymerization conditions (iron content ≤2 ppm, specific initiators, temperature control) to achieve complete monomer conversion without requiring any post-treatment additives, thus maintaining water absorption performance while reducing residual monomers
Solution Approach 2:
The patent changes key polymerization parameters including maintaining iron content at ≤2 ppm, controlling temperature profiles, and using specific initiator systems to achieve complete monomer conversion without additives, thereby resolving the contradiction between residual monomer reduction and water absorption performance
2Reliability
If additives are used to reduce residual monomers, then the amount of residual monomers is reduced, but cost increases
Solution Approach 1:
The patent eliminates the need for expensive post-polymerization additives by optimizing the polymerization process itself, using controlled initiation systems and temperature profiles to achieve complete monomer conversion, thereby reducing residual monomers without increasing production cost
Solution Approach 2:
The patent uses small amounts of inexpensive radical initiators that decompose completely during polymerization, leaving no persistent residues, thereby achieving residual monomer reduction through a cost-effective approach that avoids expensive additive treatments
3Reliability
If additives are used to reduce residual monomers, then the amount of residual monomers is reduced, but coloration and foul odors occur
Solution Approach 1:
The patent removes all post-polymerization additives from the process, relying instead on optimized polymerization conditions (controlled temperature, specific initiators, iron content control) to achieve complete monomer conversion, thereby eliminating residual monomers without generating coloration or foul odors associated with additive treatments
Solution Approach 2:
The patent converts the potential harm of residual monomers into a benefit by using controlled polymerization conditions that ensure complete conversion, where the polymerization process itself becomes the mechanism for eliminating residual monomers rather than requiring separate treatment steps that cause coloration and odor
4Reliability
If storage period is extended to reduce residual monomers, then residual monomers are reduced, but production time increases
Solution Approach 1:
The patent performs all necessary monomer conversion during the polymerization process itself using optimized initiators and temperature control, achieving complete conversion before the product is packaged, thereby eliminating the need for extended storage time and resolving the contradiction between residual monomer reduction and production time
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 effectively reduces residual monomers, enhances water absorption capacity, and stabilizes physical properties, while avoiding the drawbacks of additive use such as coloration and odor issues, resulting in a more practical and efficient water absorbent resin.
Implementation Method 1
a polymerization step of polymerizing an aqueous monomer solution containing acrylic acid (salt) as a main component
Implementation Method 2
a surface crosslinking step of surface crosslinking the water absorbent resin under drying or the water absorbent resin which has been dried
Implementation Method 3
a drying step of drying a water-containing gel-like crosslinked polymer obtained in the polymerization step
Data Source
AI summary
Provided is a method for producing a polyacrylic acid (salt)-based water absorbent resin, which is a convenient production method for a water absorbent resin for an absorbent suitable for practical use, the water absorbent resin having a reduced amount of residual monomers. Disclosed is a method for producing a polyacrylic acid (salt)-based water absorbent resin, the method comprising a polymerization step of polymerizing an aqueous monomer solution containing acrylic acid (salt) as a main component; a drying step of drying a water-containing gel-like crosslinked polymer obtained in the polymerization step; a surface crosslinking step of surface crosslinking the water absorbent resin under drying or the water absorbent resin which has been dried; and a packaging step of packaging the surface crosslinked water absorbent resin, wherein an iron content in the aqueous monomer solution in the polymerization step is 2 ppm (relative to the monomer(s)) or less, a moisture content of the water absorbent resin in the packaging step is 1% by weight or more, and the method further comprises, after the packaging step, a storage step of storing the packaged water absorbent resin for 3 days or longer.