Spray-Dried Polymer Powders for Stable Pharmaceutical Coatings
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Solution Overview
Problem
There is a need for free-flowing pulverulent film coating compositions with good redispersibility in water that maintain stable release behavior even during prolonged or thermally demanding storage, and these compositions should have small-particle dispersions with narrow particle size distributions to avoid coagulation.
Innovation Solution
A process involving the radical polymerization of N,N-diethylaminoethyl methacrylate and esters of α,β-ethylenically unsaturated mono- and dicarboxylic acids, followed by spray processing in the presence of a drying gas with specific temperature controls to produce polymer powders, which are then redispersed with acids or acidic salts to achieve the desired properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer dispersions are spray dried to produce coating powders, then binder materials with low residual monomer content are obtained, but the powders may exhibit poor flowability and agglomeration tendencies
Solution Approach 1:
The patent controls the glass transition temperature (Tg) of the polymer to be between -50°C and 150°C, and maintains the drying gas exit temperature between 40-85°C. These parameter optimizations ensure the polymer achieves optimal flowability and redispersibility while maintaining coating stability and preventing agglomeration.
Solution Approach 2:
The patent produces fine particle powders with average particle sizes of 1-100 μm through controlled spray drying. This segmentation into small particles improves flowability and prevents agglomeration, while the controlled Tg ensures the particles remain discrete and free-flowing.
2Duration of action of stationary object
If polymer powders are stored under prolonged or thermally demanding conditions, then coating durability is tested, but particle agglomeration and coagulation may occur
Solution Approach 1:
The patent incorporates stabilizing measures during the spray drying process itself, controlling the drying gas temperatures and polymer Tg to prevent agglomeration formation. This preemptive approach cushions against subsequent storage challenges, allowing the powder to maintain its particle size distribution even under prolonged or thermally demanding storage conditions.
3Productivity
If high shear forces are applied during processing, then coating application efficiency is improved, but powder agglomeration increases
Solution Approach 1:
The patent optimizes the polymer's glass transition temperature to a specific range that provides optimal balance between processability under shear and resistance to agglomeration. This parameter optimization allows the powder to withstand high shear forces during coating application while maintaining particle dispersion and avoiding agglomeration.
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 resulting polymer powders exhibit excellent flowability and redispersibility, maintaining stable release behavior and avoiding agglomeration, even under high shear forces, with particle sizes and distributions that ensure effective coating performance.
Implementation Method 1
spray processing the aqueous polymer dispersion in the presence of a drying gas to provide a powder
Implementation Method 2
providing an aqueous polymer dispersion comprising: i) as component A, a polymer obtained by radical polymerization of a) N,N-diethylaminoethyl methacrylate
Data Source
AI summary
Described are processes for producing pulverulent coating compositions comprising providing an aqueous polymer dispersion comprisingi) as component A a polymer obtained by radical polymerization ofa) N,N-diethylaminoethyl methacrylate, andb) at least one radically polymerizable compound selected from esters of α,β-ethylenically unsaturated mono- and dicarboxylic acids with C1-C8-alkanols; andspray processing the aqueous polymer dispersion in the presence of a drying gas to provide a powder, wherein the entry temperature of the drying gas into the spraying apparatus is at least 20° C. above the glass transition temperature and is at least 20° C. above the minimum film-forming temperature of the polymer and the exit temperature of the drying gas from the spraying apparatus is kept at 40 to 85° C.