Water-absorbing polymer particles color stability
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Solution Overview
Problem
Water-absorbing polymer particles used in hygiene products tend to discolor and develop unpleasant odors during storage in warm and moist environments, particularly in tropical or subtropical conditions, due to factors like residual monomers and impurities.
Innovation Solution
A process involving the use of inorganic phosphoric acid and organic 2-hydroxy acid, where the phosphorus in the phosphoric acid has an oxidation number less than +V and the 2-hydroxy acid lacks ethylenically unsaturated groups, is introduced to improve color stability and odor retention. These additives are incorporated during the production of water-absorbing polymer particles, specifically added before, during, or after polymerization and thermal surface postcrosslinking, acting synergistically to enhance properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-absorbing polymer particles are stored in warm and moist environments, then productivity and absorption capacity are maintained, but color stability deteriorates and unpleasant odors develop
Solution Approach 1:
The patent applies preliminary action by adding reducing agents (such as sodium bisulfite, sodium sulfite, or ascorbic acid) to the monomer solution before polymerization. This preliminary addition of color-stabilizing agents prevents discoloration and odor development during subsequent storage in warm and moist environments, rather than attempting to correct the problem after it occurs.
Solution Approach 2:
The patent uses reducing agents as intermediary substances that mediate between the polymerization process and the storage conditions. These reducing agents act as protective intermediaries that prevent harmful oxidation reactions during storage while allowing the polymer particles to maintain their absorption properties and productivity.
2Reliability
If reducing agents are added to improve color stability, then color stability improves, but manufacturing complexity increases
Solution Approach 1:
The patent merges the color-stabilizing function with the existing polymerization process by adding reducing agents to the monomer solution before polymerization. This integration combines multiple functions (polymerization and color stabilization) into a single process step, avoiding the need for separate color-stabilization equipment or additional processing stages.
Solution Approach 2:
The patent changes the chemical parameters of the monomer solution by adding reducing agents, which modifies the polymerization process to produce color-stable polymer particles. This parameter change approach allows color stability to be achieved through chemical modification rather than through complex physical or mechanical process changes.
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 process results in water-absorbing polymer particles with improved centrifuge retention capacity, absorption under pressure, and color stability, while preventing the development of unpleasant odors, thus maintaining product quality during prolonged storage in adverse conditions.
Implementation Method 1
adding inorganic reducing agents... the inorganic reducing agents can be added, for example, to the polymer gel after the polymerization
Implementation Method 2
water-absorbing polymer particles... The water-absorbing polymer particles are also referred to as superabsorbents
Implementation Method 3
The production of water-absorbing polymer particles is described in the monograph 'Modern Superabsorbent Polymer Technology'
Data Source
AI summary
A process for producing water-absorbing polymer particles, wherein at least one inorganic phosphoric acid and/or salt thereof and at least one organic 2-hydroxy acid and/or salt thereof is added, where the phosphorus in the inorganic phosphoric acid has an oxidation number of less than +V and the organic 2-hydroxy acid does not have any ethylenically unsaturated groups, and also the water-absorbing polymer particles obtainable by the process according to the invention.