Esterified Cellulose Ether Aqueous Dispersion Film Formation
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Solution Overview
Problem
Existing aqueous dispersions of enteric polymers like HPMCAS often require high amounts of plasticizers, result in unstable suspensions, and leave residual alkaline materials that jeopardize the enteric properties of final films, limiting their concentration and efficiency in film formation.
Innovation Solution
An aqueous composition with at least 10 weight percent of dispersed esterified cellulose ether, partially neutralized with ammonium salts, which is ground or emulsified in an aqueous diluent to achieve stable dispersions with improved film-forming properties and reduced plasticizer needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high concentration of enteric polymer is used in aqueous dispersion, then film-forming efficiency is improved, but stability of suspension deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting the particle size distribution (d90 ≤ 10 micrometers) and chemical structure of the esterified cellulose ether to enable high-concentration dispersions to remain stable. This resolves the contradiction by modifying physical parameters that allow both high productivity and suspension stability.
2Object-affected harmful factors
If aqueous solutions of enteric polymers are used, then organic solvents are eliminated, but the concentration of polymer is limited to 4-6 percent
Solution Approach 1:
The patent changes the physical state parameter from molecular dissolution to colloidal dispersion, enabling polymer concentrations of at least 10 wt% (exceeding the 4-6% limit) in aqueous media without requiring organic solvents. This resolves the contradiction between eliminating harmful organic solvents and maintaining high polymer concentration.
3Ease of manufacture
If dilute aqueous solutions are used, then polymer dissolution is achieved, but drying time and energy consumption increase
Solution Approach 1:
The patent changes the concentration parameter to at least 10 wt%, which is sufficiently concentrated to reduce drying time and energy consumption while maintaining ease of manufacture through the stable dispersion formulation. This resolves the contradiction between ease of manufacture and drying efficiency.
4Strength
If large amount of plasticizer is added to aqueous dispersion, then film flexibility is improved, but the dispersion stability and enteric properties are jeopardized
Solution Approach 1:
The patent extracts or eliminates the need for large amounts of plasticizers by using specifically formulated esterified cellulose ethers with controlled particle size and structure that provide inherent film-forming capability without compromising dispersion stability or enteric properties. This resolves the contradiction between film flexibility and dispersion stability.
5Adaptability or versatility
If esterified cellulose ether is dispersed in aqueous diluent, then organic solvents are replaced, but particle size control is required for stable dispersion
Solution Approach 1:
The patent specifies precise particle size parameters (d90 ≤ 10 micrometers) as a key parameter change that enables stable aqueous dispersion while maintaining versatility and adaptability of the esterified cellulose ether system. This resolves the contradiction between aqueous compatibility and manufacturing precision requirements.
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 approach allows for high-concentration aqueous dispersions with enhanced film transparency and stability, reducing the need for plasticizers and minimizing residual alkaline materials, thus improving the enteric properties and processing efficiency of cellulose ether-based coatings and capsules.
Implementation Method 1
aqueous composition with at least 10 weight percent of dispersed esterified cellulose ether
Implementation Method 2
which is ground or emulsified in an aqueous diluent to achieve stable dispersions
Implementation Method 3
partially neutralized with ammonium salts of carbonic acid, formic acid or acetic acid
Data Source
AI summary
An aqueous composition comprising at least 10 weight percent of a dispersed esterified cellulose ether, based on the total weight of the aqueous composition, wherein the esterified cellulose ether comprises (i) groups of the formula -C(O) - R - COOH or (ii) a combination of aliphatic monovalent acyl groups and groups of the formula -C(O) - R - COOH, R being a divalent aliphatic or aromatic hydrocarbon group, and at least a part of the groups -C(O) - R - COOH are neutralized with an ammonium salt of carbonic acid, formic acid or acetic acid, and wherein d90 of the dispersed esterified cellulose ether particles is up to 10 micrometers, d90 being the diameter where 90 mass percent of the particles have a smaller equivalent diameter and the other 10 mass percent have a larger equivalent diameter, is useful for preparing coating dosage forms including tablets, capsules and others, or for the formation of capsules shells.