Superabsorbent Metering via Cohesion Control Agent
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Solution Overview
Problem
Accurate and high-speed metering of superabsorbents is challenging due to their particulate nature, which impedes free flow and forced feeding, especially in diaper-forming machines, where precise and continuous delivery is required to maintain high production line speeds.
Innovation Solution
A process utilizing a screw conveyor with a selected unconfined yield strength of 0.75 to 1.5 kPa at a consolidation stress of 6 kPa, combined with a cohesion control agent, ensures steady, non-pulsating flow and accurate metering of superabsorbents, achieving a maximum standard deviation of 10% or less in the amount or rate delivered.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If superabsorbents are metered using conventional screw conveyors, then the metering process can be performed, but the flow is unstable and pulsating due to poor flowability of the particulate material
Solution Approach 1:
The patent changes the physical parameters of the superabsorbent material by adding a liquid binder that modifies the interparticle forces. This changes the material's flow characteristics from poor and pulsating to stable and continuous, enabling reliable metering without altering the screw conveyor design
Solution Approach 2:
The liquid binder acts as an intermediary substance between the superabsorbent particles. It modifies the interaction between particles by creating capillary bridges and adhesive forces, which transform the bulk material's flow behavior from unstable to stable, enabling continuous feeding
2Productivity
If the screw conveyor speed is increased to maintain high production line speeds, then productivity increases, but metering accuracy deteriorates due to pulsating flow
Solution Approach 1:
By adding the liquid binder, the material's flow parameters are fundamentally changed. This allows the system to operate at higher screw conveyor speeds while maintaining stable material flow, thus achieving both high productivity and accurate metering simultaneously
3Ease of manufacture
If superabsorbent particles are used in their conventional dry state, then storage and handling are simplified, but forced feeding becomes difficult due to particulate nature
Solution Approach 1:
The patent changes the physical state of the superabsorbent material by introducing a liquid binder that creates agglomerates with improved flow properties. This transformation maintains the simplicity of handling dry materials while enabling effective forced feeding through the modified flow characteristics
Data Source
AI summary
Superabsorbents are metered by a process using a screw conveyor, wherein the superabsorbent is selected, or treated with a cohesion control agent, to have an unconfined yield strength of from 0.75 to 1.5 kPa at consolidation stress of 6 kPa.