Cellulose Derivative Grinding for Bulk Density and Flowability
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Solution Overview
Problem
Cellulose derivatives in particulate form face challenges with poor flowability and low onset dissolution temperature, leading to issues in manufacturing and effectiveness in applications such as sustained release dosage forms, where they form lumps and require time-consuming hot/cold water dissolution techniques.
Innovation Solution
A process involving grinding and drying a moist cellulose derivative in a gas-swept impact mill, followed by additional drying outside the mill, to achieve improved flowability and onset dissolution temperature, with a moisture content of 60 to 95% and a median Equivalent Projected Circle Diameter of less than 140 micrometers, resulting in enhanced bulk density and Carr Index.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If water-soluble cellulose derivatives are supplied as particulate dry material, then they are convenient for storage and transport, but they form lumps and require time-consuming hot/cold water dissolution techniques due to gel-blocking behavior
Solution Approach 1:
The patent applies parameter changes by modifying the particle size distribution (median EQPC less than 140 micrometers) and moisture content (60-95%) of the cellulose derivative particles. These parameter changes result in improved dissolution behavior with onset dissolution temperatures of at least 61.5°C, eliminating the gel-blocking effect and allowing direct dissolution in cold water without time-consuming hot/cold water techniques
2Duration of action of moving object
If cellulose ether particles are made very small (less than 105 micrometers) to achieve sustained release profiles, then release duration is extended, but flowability deteriorates leading to manufacturing problems
Solution Approach 1:
The patent resolves this contradiction by optimizing the particle size parameter to have a median Equivalent Projected Circle Diameter (EQPC) of less than 140 micrometers, which is larger than the conventional fine particles (less than 105 micrometers) used for sustained release. This parameter change maintains the sustained release profile while significantly improving flowability, as evidenced by the Carr Index of 30 or less and untapped bulk density of at least 0.40 g/cm³
Solution Approach 2:
The patent applies partial action by using particles that are not as fine as the conventional extreme (105 micrometers or smaller), but still sufficiently small to provide sustained release. This partial approach to particle size reduction achieves the desired release duration without the excessive fineness that causes poor flowability
3Productivity
If cellulose derivatives have low onset dissolution temperature, then they dissolve quickly in cold water, but they require hot water treatment to overcome gel-blocking behavior
Solution Approach 1:
The patent applies parameter changes by controlling the moisture content (60-95%) and particle size (median EQPC less than 140 micrometers) during production. These parameter changes result in an increased onset dissolution temperature of at least 61.5°C, which prevents gel-blocking and allows rapid dissolution in cold water without requiring hot water treatment, thus maintaining high productivity
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 significantly increases the flowability and onset dissolution temperature of cellulose derivatives, achieving an untapped bulk density of at least 0.40 g/cm³ and a Carr Index of 30 or less, improving their performance in pharmaceutical and other applications by reducing lump formation and enhancing manufacturing efficiency.
Implementation Method 1
grinding and partially drying the moist cellulose derivative in a gas-swept impact mill
Implementation Method 2
gas-swept impact mill
Implementation Method 3
contacting the ground and partially dried cellulose derivative with an additional amount of a drying gas outside the impact mill
Data Source
Figure 1
AI summary
A particulate cellulose derivative is obtained in a process of grinding and drying a moist cellulose derivative which comprises the steps of A) providing a cellulose derivative having a moisture content of from 60 to 95 percent, based on the total weight of the moist cellulose derivative, B) grinding and partially drying the moist cellulose derivative in a gas-swept impact mill; and C) contacting the ground and partially dried cellulose derivative with an additional amount of a drying gas outside the gas-swept impact mill. The obtained particulate cellulose derivative has a high untapped bulk density and a good flowability.