HPMCP Production With Acetic Acid Removal for Better Flowability
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Solution Overview
Problem
Conventional methods for producing hydroxypropyl methyl cellulose phthalate (HPMCP) result in high acetic acid content in waste water, leading to increased chemical oxygen demand, pH lowering, odor issues, and flowability problems due to clogging and hopper residue, necessitating extensive waste water treatment and affecting production efficiency.
Innovation Solution
A method involving esterification of hydroxypropyl methyl cellulose with phthalic anhydride in acetic acid, followed by water addition, acetic acid removal, and a wash and recovery step to produce HPMCP with reduced acetic acid content, resulting in spherical particles with improved flowability and reduced waste treatment burden.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If water is added to the reaction product solution to precipitate HPMCP, then HPMCP can be recovered through filtration, but the waste water contains high levels of acetic acid requiring extensive treatment
Solution Approach 1:
The patent extracts acetic acid from the reaction product solution before adding water for precipitation. This is achieved through extraction with an organic solvent (such as toluene or xylene) that selectively dissolves acetic acid, separating it from the HPMCP-containing aqueous phase. The extracted acetic acid can then be recovered and reused, while the waste water contains minimal acetic acid requiring little treatment.
Solution Approach 2:
The patent recovers acetic acid from the reaction process by extracting it with an organic solvent. The extracted acetic acid is then separated from the solvent (through distillation or other separation methods) and can be reused in subsequent esterification reactions. This reduces both waste treatment costs and raw material consumption.
2Object-generated harmful factors
If the amount of acetic acid is reduced to lower waste treatment burden, then waste water treatment cost decreases, but cellulose dissolution becomes insufficient
Solution Approach 1:
The patent uses an extraction solvent (toluene, xylene, or other organic solvents) as an intermediary substance to remove acetic acid from the reaction mixture. This intermediary step allows the process to use sufficient acetic acid for complete cellulose dissolution and reaction, while the extraction step subsequently removes the excess acetic acid before waste water discharge, resolving the contradiction between reaction efficiency and waste treatment.
3Device complexity
If conventional HPMCP is produced without acetic acid removal, then production process is simple, but flowability is poor causing hopper clogging and residue
Solution Approach 1:
The patent extracts acetic acid from the reaction product solution using an organic solvent before water addition and precipitation. This removal of acetic acid modifies the HPMCP particle formation process, resulting in particles with improved flowability characteristics. The extracted HPMCP shows reduced tendency to clog hoppers and pipes, and can be completely discharged without residue, despite the added extraction step.
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 reduces acetic acid in the waste water, enhances HPMCP flowability, improves mixing uniformity with drugs in hot-melt extrusion, and minimizes hopper clogging, facilitating continuous operation and reducing production costs.
Implementation Method 1
an esterification step of esterifying hydroxypropyl methyl cellulose with phthalic anhydride in acetic acid as a solvent to obtain a reaction product solution containing hydroxypropyl methyl cellulose phthalate
Implementation Method 2
water is added to a reaction product solution to obtain a suspension having HPMCP precipitated
Data Source
AI summary
There is provided a method for efficiently produce hydroxypropyl methyl cellulose phthalate (HPMCP) having excellent flowability, where acetic acid in a reaction product mixture subjected to a wash and recovery step can be reduced. More specifically, there is provided a method for producing HPMCP including an esterification step of esterifying hydroxypropyl methyl cellulose (HPMC) with phthalic anhydride in acetic acid as a solvent to obtain a reaction product solution containing HPMCP; a water addition step of adding water to the reaction product solution to obtain a water-added reaction product solution; an acetic acid removal step of removing at least a portion of the acetic acid from the water-added reaction product solution to obtain a mixture having an acetic acid content reduced; and a wash and recovery step of washing the mixture and recovering the HPMCP.