PVDF Particle Formation via Solvent Phase Transition
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Solution Overview
Problem
Current methods for producing polyvinylidene difluoride (PVDF) or copolymer particles struggle to achieve a population with a narrow range of spherical particle sizes without the application of a selection process, often resulting in irregularly shaped particles that are not ideal for additive manufacturing and lacquer production.
Innovation Solution
A method involving dissolving PVDF in an organic solvent with specific characteristics, such as diethylene glycol monobutyl ether acetate, where the solvent is heated until the polymer completely dissolves, then cooled to form uniform, spherical particles with a controlled particle size distribution between 5 μm to 200 μm, eliminating the need for post-processing selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to produce PVDF particles, then particle production is achieved, but the particles have irregular shapes and broad size distribution requiring selection processes
Solution Approach 1:
The invention changes the chemical parameters of the solvent system by using specific fluorinated solvents (perfluorinated cyclic carbonate, perfluorinated cycloaliphatic carbonate, or perfluorinated aromatic carbonate) with defined molecular structures and weights. This parameter change in solvent chemistry enables controlled polymer dissolution and precipitation that produces spherical particles with narrow size distribution (span < 1.3) without requiring selection processes.
Solution Approach 2:
The invention utilizes phase transition of the polymer-solvent system by controlling the temperature at which the polymer precipitates from the fluorinated solvent. By maintaining the solution at a controlled temperature range (20-80°C) and allowing controlled cooling, the polymer transitions from dissolved state to precipitated spherical particles, achieving uniform particle formation through phase change control.
2Shape
If conventional solvents are used, then particle formation is achieved, but particle sphericity is poor and packing density is reduced
Solution Approach 1:
The invention changes the physical and chemical parameters of the solvent by selecting fluorinated solvents with specific molecular weights (100-500 g/mol) and structures. These parameter changes in solvent properties enable the formation of spherical particles with high sphericity (>0.85) and controlled size distribution, which directly improves packing density and eliminates the need for selection processes.
3Manufacturing precision
If post-processing selection is applied, then particle size uniformity is improved, but production time and complexity increase
Solution Approach 1:
The invention performs the particle size control action during the formation process itself rather than after. By controlling the precipitation conditions (temperature, solvent composition, mixing rate) during particle formation, the method produces uniform particles with narrow size distribution (span < 1.3) directly, eliminating the need for subsequent selection processes and reducing production time.
4Ease of manufacture
If irregular particles are produced, then manufacturing is simpler, but flowability and additive manufacturing performance deteriorate
Solution Approach 1:
The invention uses controlled phase transition of the polymer from dissolved to precipitated state through temperature control. By maintaining the solution at controlled temperatures (20-80°C) and allowing controlled cooling, spherical particles form directly through phase change, achieving both manufacturing simplicity and improved flowability without requiring complex post-processing.
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 produces particles with a high sphericity and narrow particle size distribution, enhancing their packing density, flowability, and suitability for additive manufacturing and lacquer production, reducing the need for additional processing steps and improving product precision.
Implementation Method 1
The polymer is dissolved in an organic solvent
Implementation Method 2
cooling the solution to a temperature at which the polymer particles are formed
Implementation Method 3
the polymer particles re-crystalize from the mixture
Data Source
AI summary
The invention concerns a method for producing a population of particles of a polymer, wherein the polymer is polyvinylidene difluoride (=PVDF) or a copolymer comprising polyvinylidene difluoride, wherein the polymer is dissolved in an organic solvent, wherein molecules of the solvent comprise or consist of 3 to 22 carbon atoms, one or more oxygen atom(s) as heteroatom(s) and at most one carbocyclic or heterocyclic residue comprising carbon atoms which carbocyclic or heterocyclic residue is an aromatic residue, wherein the carbon atoms in the carbocyclic or heterocyclic residue are carbon atoms taken from said 3 to 22 carbon atoms, wherein the one or more oxygen atom(s) is/are part of at least one carboxylic acid ester group or carbonyl group, wherein the carbon atom in the carboxylic acid ester group and the carbonyl group is one of said 3 to 22 carbon atoms or/and at least one ether group and at most three hydroxyl groups, wherein in case of presence of at least one hydroxyl group the number of ether groups always exceeds the number of hydroxyl groups, wherein in case of presence of only 3 carbon atoms the molecule comprises additionally at least one pseudohalogen or additionally at least one further heteroatom selected from halogen, N, B, P and S, wherein the method comprises heating the solvent and the solid polymer immersed in the solvent at least until the polymer completely dissolves, cooling the solution until polymer particles are formed, and separating the particles formed during step b) from the solution or from a gel formed from the solution during step b).