Continuous Multi-Zone Drying of Flexible Dissolvable Sheets for Uniform Pores
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Solution Overview
Problem
Existing processes for manufacturing flexible, porous, dissolvable solid sheets face challenges in achieving uniform pore size distribution, manufacturing rate, and thickness, particularly in belt-based continuous processes, while drum drying struggles with thick sheets and non-uniformity.
Innovation Solution
A continuous process involving a conveying belt that passes through multiple heating zones with specific temperature gradients (Tb1 > Tt1; Tb1 > Tb2; Tt1 < Tt2) to dry a wet pre-mixture of water-soluble polymer and surfactant, forming a sheet with controlled heating durations and aeration to achieve uniform pore size and thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If drum-drying process is used to make flexible, porous, dissolvable solid sheet, then uniform pore size distribution is achieved, but manufacturing rate is limited to 5-10 kg per hour per drum
Solution Approach 1:
The drying process is segmented into multiple heating zones (first heating zone and second heating zone) with different temperature profiles. The first heating zone uses Tb1>Tt1 to prevent surface cracking, while the second heating zone uses Tt2>Tb2 to accelerate drying. This segmentation allows the process to achieve both uniform pore structure and high production rate.
Solution Approach 2:
The patent changes the temperature parameters throughout the drying process by using different bottom and top heating temperatures in different zones. Specifically, Tb1>Tt1 in the first zone and Tt2>Tb2 in the second zone, with Tb1>Tb2 and Tt1<Tt2. This parameter variation enables control over drying rate and pore uniformity simultaneously, resolving the contradiction between manufacturing precision and productivity.
2Productivity
If belt-based continuous process is used to achieve high manufacturing rate, then productivity increases, but pore size distribution becomes non-uniform
Solution Approach 1:
The continuous belt drying process is divided into multiple heating zones with distinct temperature profiles. The first heating zone (Tb1>Tt1) ensures uniform pore formation, while the second heating zone (Tt2>Tb2) maintains high drying efficiency. This segmentation preserves the uniform pore size distribution while achieving high manufacturing rates characteristic of continuous processes.
Solution Approach 2:
The patent implements dynamic parameter changes by varying both temperature and position throughout the drying process. The temperature profile transitions from Tb1>Tt1 in the first zone to Tt2>Tb2 in the second zone, with Tb1>Tb2 and Tt1<Tt2. These parameter changes enable the belt-based continuous process to achieve both high productivity and uniform pore size distribution.
3Ease of manufacture
If drum drying is used to make thin sheet (around 1 mm), then ease of manufacture is maintained, but ability to make thick solid sheet is challenging
Solution Approach 1:
The patent uses parameter changes in temperature profiles (Tb1>Tt1 followed by Tt2>Tb2 with Tb1>Tb2 and Tt1<Tt2) to control the drying rate and moisture gradient throughout the sheet thickness. This enables the process to handle both thin sheets (around 1 mm) and thick sheets uniformly, expanding the adaptability while maintaining ease of manufacture through a standardized multi-zone drying approach.
4Reliability
If pore size is made large to improve dissolution performance, then dissolution rate increases, but juice or paste may leak from multilayered sheet during storage
Solution Approach 1:
The controlled temperature parameter changes (Tb1>Tt1 followed by Tt2>Tb2 with Tb1>Tb2 and Tt1<Tt2) throughout the drying process create an optimal pore size distribution that balances dissolution performance and leakage prevention. The gradual temperature variation produces a uniform porous structure with appropriate pore sizes that allow rapid dissolution while maintaining structural integrity during storage, preventing juice or paste leakage.
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 produces a thick, uniformly structured sheet with consistent pore size distribution, balancing dissolution and leakage, achieving a 20-fold increase in manufacturing rate compared to drum drying.
Implementation Method 1
drying said formed sheet of aerated wet pre-mixture on a conveying belt with the bottom side of said formed sheet contacting said conveying belt, wherein the conveying belt is configured to sequentially pass through multiple heating zones with heating temperatures ranging from 70° C. to 200° C.
Implementation Method 2
multiple heating zones with heating temperatures ranging from 70° C. to 200° C.; wherein said multiple heating zones comprises a first heating zone and a second heating zone
Data Source
AI summary
A continuous process for preparing a sheet article includes preparing a wet pre-mixture comprising a water-soluble polymer and a surfactant and having a viscosity of from 1,000 cps to 25,000 cps measured at 40° C. and 1 s−1; aerating said wet pre-mixture to form an aerated wet pre-mixture having a density of from 0.05 to 0.5 g/ml; forming said aerated wet pre-mixture into a sheet having a top side and a bottom side; and drying said formed sheet of aerated wet pre-mixture on a conveying belt with the bottom side of said formed sheet contacting said conveying belt.