HPMCP Composition for Lower Acetic Acid and 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 poor flowability, causing clogging and sanitary problems in hoppers and pipes.
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.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the amount of acetic acid is reduced in the esterification step, then the waste water treatment burden is reduced, but it becomes difficult to uniformly dissolve the cellulose in the acetic acid solvent at high concentration
Solution Approach 1:
The patent applies preliminary action by adding water to the reaction mixture before the washing step. This preliminary water addition causes acetic acid to separate from the reaction mixture in advance, so that subsequent washing requires less water and generates less wastewater. The acetic acid separation occurs before the main washing operation, preemptively reducing the burden on waste water treatment while maintaining proper dissolution conditions during the reaction.
2Ease of manufacture
If conventional HPMCP is used, then the production process is simple, but the flowability is poor causing clogging and sanitary problems
Solution Approach 1:
The patent applies parameter changes by modifying the particle morphology parameters of HPMCP through controlled acetic acid separation and washing conditions. This transforms the particle shape and size distribution, converting fibrous or irregular particles into more spherical particles with better flow characteristics. The parameter changes in particle morphology directly improve flowability and prevent clogging while maintaining production simplicity.
3Ease of manufacture
If water is added to the reaction product solution to obtain a suspension, then HPMCP precipitates and can be washed, but a large amount of acetic acid ends up in the waste water
Solution Approach 1:
The patent applies preliminary action by adding water to the reaction mixture before the washing step. This preliminary water addition causes acetic acid to separate from the reaction mixture in advance, so that subsequent washing requires less water and generates less wastewater. The acetic acid separation occurs before the main washing operation, preemptively reducing the burden on waste water treatment while maintaining proper dissolution conditions during the reaction.
Solution Approach 2:
The patent applies phase transitions by utilizing the immiscibility of acetic acid with water to separate acetic acid from the reaction mixture. When water is added, the system undergoes phase separation where acetic acid forms a distinct phase that can be removed before washing. This phase transition approach efficiently separates the harmful acetic acid component while allowing HPMCP to remain in the solid phase for subsequent washing and recovery.
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
Reduces waste water treatment burden, enhances flowability, improves mixing uniformity with drugs in hot-melt extrusion, and prevents bridge formation, ensuring continuous operation and uniform drug content.
Implementation Method 1
an acetic acid removal step of removing at least a portion of the acetic acid from the water-added reaction product solution
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.