Rocking-Type Sieve Classification for Water Absorbent Resin

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Solution Overview

Problem

Existing methods for producing polyacrylic acid (salt)-based water absorbent resins face challenges in maintaining high liquid permeability and physical properties, especially at large scales, due to increased costs and decreased efficiency from the addition of surface crosslinking agents and additives, which can lead to sieve net breakage and decreased classification efficiency.

Innovation Solution

A method involving a rocking-type sieve classification apparatus with a predetermined trajectory and double screen configuration to improve classification efficiency and reduce fine powder, enhancing liquid permeability and producibility of the water absorbent resin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If surface crosslinking agents and additives are added to improve liquid permeability, then liquid permeability is improved, but production costs increase and sieve net breakage occurs

Engineering Contradiction:
Improveliquid permeabilityVSAvoidproduction cost
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and removes the harmful additives (surface crosslinking agents and additives) from the production process. By classifying and separating particles during the drying stage, the patent achieves the desired liquid permeability without requiring additional chemical agents, thus reducing production costs and eliminating sieve net breakage caused by these additives.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs particle classification during the drying stage, before the final product is completed. By pre-classifying particles at this intermediate stage, the invention achieves the desired particle size distribution and liquid permeability properties early in the process, eliminating the need for subsequent additive treatments and reducing overall production complexity.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If surface crosslinking agents and additives are added to improve liquid permeability, then liquid permeability is improved, but classification efficiency decreases

Engineering Contradiction:
Improveliquid permeabilityVSAvoidclassification efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The invention removes the need for surface crosslinking agents and additives by implementing a classification system that operates during the drying stage. This extraction of harmful substances restores classification efficiency to high levels while maintaining improved liquid permeability properties.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

By performing classification during the drying stage rather than after product completion, the patent achieves efficient particle separation before additives would interfere with the process. This preliminary classification action maintains high productivity while achieving the desired liquid permeability.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If production scale is increased to improve productivity, then productivity is improved, but liquid permeability and physical properties become unstable

Engineering Contradiction:
Improveproduction scaleVSAvoidphysical property stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent implements particle classification during the drying stage, which is an intermediate stage accessible at all production scales. By performing this classification action early in the process, the invention ensures consistent particle size distribution and physical properties regardless of production scale, maintaining reliability while enabling high productivity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The classification system operates autonomously during the drying stage without requiring additional external agents or complex interventions. This self-service mechanism ensures consistent physical properties at any production scale, as the classification process inherently maintains product quality without being affected by production volume.

Inventive Principle:
Principle #25Self-service

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 stabilizes the physical properties, particularly liquid permeability, and improves producibility of polyacrylic acid (salt)-based water absorbent resins, even at large scales, by optimizing the classification process and reducing equipment costs.

Implementation Method 1

a rocking-type sieve classification apparatus with a predetermined trajectory

Methodology Applied
Scientific EffectVibration: Vibration

Implementation Method 2

a rocking-type sieve classification apparatus with a predetermined trajectory and double screen configuration to improve classification efficiency

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP2881420B1Process for producing polyacrylic acid (SALT)-based water-absorbing resin
Publication Date: 2022.10.19 NIPPON SHOKUBAI CO LTD
  • EP2881420B1 patent drawingFigure 1~2
  • EP2881420B1 patent drawingFigure 3~4
  • EP2881420B1 patent drawingFigure 5

AI summary

Provided is a method for producing a polyacrylic acid (salt)-based water absorbent resin in which the physical properties (especially liquid permeability) are improved and maintained even in large scale production. The method for producing a polyacrylic acid (salt)-based water absorbent resin, which sequentially includes a polymerization step, in which a monomer aqueous solution having acrylic acid (salt) as a main component is polymerized, a drying step, in which a water-containing gel-like crosslinked polymer obtained in the polymerization step is dried, and a classification step, in which a polymer obtained in the drying step is classified, wherein a rocking-type sieve classification apparatus is used in the classification step, and the rocking-type sieve classification apparatus has a sieve net having a trajectory and a rotation speed in the following ranges; radial gradient R: from 5 to 40 mm, tangential gradient T: from 0.1 to 25 mm, eccentric gradient E: from 40 to 80 mm, and rotation speed F: from 60 to 600 rpm.