HPMCAS Production via Precipitation and Centrifugal Decanting
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Solution Overview
Problem
The production of hypromellose acetate succinate (HPMCAS) is hindered by its heat sensitivity, leading to fusion and adhesion during pulverization, resulting in excessively small particle sizes when using conventional pulverizers, which complicates achieving the desired average particle size range of 70 to 300 µm.
Innovation Solution
A method involving esterification of hypromellose with esterification agents, followed by mixing with water to precipitate crude HPMCAS, and subsequent liquid removal using a centrifugal decanter to reduce particle size without the need for pulverization, achieving an average particle size of 70 to 400 µm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional pulverization is used to reduce particle size, then particle size can be reduced, but heat generated during pulverization causes fusion and adhesion of heat-sensitive HPMCAS particles
Solution Approach 1:
The patent replaces the mechanical pulverization system with a chemical precipitation system. Instead of using mechanical force to reduce particle size, the invention uses controlled chemical precipitation from solution to form particles of desired size directly, thereby eliminating the harmful thermal effects of mechanical grinding while achieving the required particle size reduction
Solution Approach 2:
The invention changes the physical state and formation parameters of HPMCAS particles. Rather than starting with bulk material and reducing size mechanically, the process dissolves HPMCAS in a solvent and then controls precipitation conditions (such as adding non-solvent, controlling temperature and agitation) to form particles of target size directly, thus avoiding heat-induced fusion
2Object-affected harmful factors
If pulverizer structure is modified to cool material and prevent fusion, then adhesion is suppressed, but particle size becomes excessively small
Solution Approach 1:
The invention inverts the conventional approach by not starting with large particles and reducing them, but rather starting with dissolved material and forming particles of desired size directly through controlled precipitation. This reverse approach eliminates the need for cooling measures and prevents over-reduction of particle size
3Manufacturing precision
If pulverization step is added to achieve desired particle size, then particle size range can be controlled, but production process becomes more complex and facility cost increases
Solution Approach 1:
The invention merges the particle size control function into the precipitation process itself. By controlling precipitation conditions (solvent composition, temperature, agitation rate, addition rate), the desired particle size range is achieved as an integral part of the production process, eliminating the need for separate pulverization equipment and simplifying the overall manufacturing system
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
This method effectively reduces the average particle size of HPMCAS without a pulverization step, simplifies the production process, reduces facility costs, and shortens drying time, while ensuring the product meets the intended particle size range for improved flowability and miscibility with drugs.
Implementation Method 1
subjecting the suspension to liquid removal (solid-liquid separation) with a centrifugal decanter (also called 'decanter type centrifugal separator')
Implementation Method 2
reacting hypromellose with an esterification agent, mixing the resulting reaction solution with water to obtain a suspension containing precipitated crude hypromellose acetate succinate
Implementation Method 3
mixing the resulting reaction solution with water to obtain a suspension containing precipitated crude hypromellose acetate succinate
Data Source
Figure 1
AI summary
Provided is a method for producing HPMCAS capable of reducing the average particle size of HPMCAS particles to an intended range without a pulverization step. Specifically provided is a method for producing hypromellose acetate succinate, comprising an esterification step of reacting hypromellose with an esterification agent in the presence of a catalyst to obtain a reaction solution containing crude hypromellose acetate succinate, a precipitation step of mixing the reaction solution with water to precipitate the crude hypromellose acetate succinate, thereby obtaining a hypromellose acetate succinate suspension, a liquid removal step of removing a liquid from the hypromellose acetate succinate suspension with a centrifugal decanter to obtain liquid-removed hypromellose acetate succinate, and a drying step of drying the liquid-removed hypromellose acetate succinate.