Particulate Water Absorbent Agent Surface Crosslinking

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Solution Overview

Problem

Conventional methods for manufacturing particulate water absorbent agents often fail to achieve a high water absorption ratio and rate while maintaining moisture absorption fluidity under high humidity conditions and absorption against pressure.

Innovation Solution

Increasing grinding energy during the gel grinding process and incorporating moisture absorption fluidity improving agents such as multi-component metal compounds with a hydrotalcite structure and water insoluble metal phosphate to enhance the physical properties of the particulate water absorbent agents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional manufacturing methods are used for particulate water absorbent agents, then production is simpler and cost-effective, but the water absorption ratio and rate cannot be simultaneously optimized while maintaining moisture absorption fluidity under high humidity

Engineering Contradiction:
Improvewater absorption ratio and rateVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by performing surface crosslinking treatment on the water absorbent resin particles before final product formation. This pre-treatment modifies the surface properties to control moisture absorption characteristics, enabling the particles to maintain fluidity under high humidity while achieving high water absorption ratio and rate. The surface crosslinking is performed as a preliminary step that sets the foundation for subsequent performance optimization.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent utilizes parameter changes by carefully controlling the surface crosslinking degree and particle size distribution to achieve optimal performance. By adjusting the crosslinking parameters (such as crosslinking agent concentration, treatment time, and temperature) and particle size parameters, the invention optimizes the balance between water absorption capability and moisture fluidity, resolving the contradiction between high absorption performance and manufacturing simplicity.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If surface crosslinking is performed to improve water absorption ratio, then absorption performance increases, but moisture absorption fluidity under high humidity conditions deteriorates

Engineering Contradiction:
Improvewater absorption ratioVSAvoidmoisture absorption fluidity
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies local quality by performing surface crosslinking only on the outer layer of the water absorbent resin particles rather than throughout the entire particle structure. This creates a differentiated structure where the surface has crosslinked properties for controlled moisture interaction, while the internal structure remains highly absorbent. The surface crosslinking layer acts as a selective barrier that maintains fluidity while enabling high water absorption ratio.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent applies partial action by using controlled surface crosslinking with specific crosslinking agents and conditions to achieve just enough surface modification to improve water absorption ratio without excessive crosslinking that would harm moisture fluidity. The crosslinking is performed to a specific degree (partial action) rather than complete crosslinking, optimizing the balance between absorption performance and fluidity under high humidity.

Inventive Principle:
Principle #16Partial or excessive action

3Speed

If grinding energy is increased to improve water absorption rate, then absorption rate increases, but particle size distribution and physical properties may be compromised

Engineering Contradiction:
Improvewater absorption rateVSAvoidparticle size distribution
Core Design Contradiction:
SpeedVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by performing surface crosslinking treatment before the grinding process. This pre-treatment strengthens the particle structure and surface properties, enabling the particles to withstand higher grinding energies without excessive fragmentation or loss of physical properties. The preliminary crosslinking creates a robust structure that maintains particle integrity during high-energy grinding, allowing optimization of water absorption rate while controlling particle size distribution.

Inventive Principle:
Principle #10Preliminary action

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 approach results in particulate water absorbent agents with improved water absorption ratio, rate, and moisture absorption fluidity, effectively addressing the limitations of conventional methods by ensuring better performance under high humidity and pressure conditions.

Implementation Method 1

incorporating moisture absorption fluidity improving agents such as multi-component metal compounds with a hydrotalcite structure and water insoluble metal phosphate

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 2

particulate water absorbent agent having both a high water absorption ratio and a high water absorption rate

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP3437732B1Particulate water absorbing agent
Publication Date: 2022.05.11 NIPPON SHOKUBAI CO LTD
  • EP3437732B1 patent drawingFigure 1~3
  • EP3437732B1 patent drawingFigure 4~5
  • EP3437732B1 patent drawing

AI summary

The purpose of the present invention is to provide a particulate water absorbing agent having both a high water absorption multiplying factor and a high water absorption rate and a method for manufacturing the same. The present invention is a particulate water absorbing agent for which CRC is 30 to 50 g/g, wherein the weight average particulate diameter (D50) is 200 -600 µm, and the DRC index given by the following formula is a specific value (for example, 43, 30, or 20) or less: DRC index = (49 - DRC5min [g/g])/(D50 [um]/1000).