Thermoplastic Polyester Particles Melt Emulsion Spherical Morphology

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Solution Overview

Problem

Current methods for producing thermoplastic polyester particles for additive manufacturing often result in irregular shapes and wide particle size distributions, leading to poor powder flow and packing efficiency, which can cause structural weak points and void formation in 3-D printed objects.

Innovation Solution

A method involving a melt emulsion with a continuous phase, a dispersed phase, and an inner phase of thermoplastic polyester, where the phases are immiscible and processed at high shear rates above the melting point, followed by cooling to form solidified particles with a narrow sintering window, enhancing flow properties and packing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If commercial powder particulates are obtained by cryogenic grinding or precipitation processes, then production efficiency is improved, but irregular particulate shapes and wide particle size distributions result, leading to poor powder flow performance

Engineering Contradiction:

Improveproduction efficiencyVSAvoidparticulate shape regularity and size distribution

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The invention utilizes phase transition by melting the thermoplastic polyester above its melting point to form a melt emulsion, then cooling it below the melting point to solidify into spherical particles. This phase change approach naturally produces uniform spherical shapes with narrow size distributions, eliminating the shape irregularity problem associated with cryogenic grinding while maintaining high production efficiency.

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The invention replaces the mechanical cryogenic grinding system with a thermal processing system. Instead of using mechanical force to grind particles at low temperatures, the process uses heating above the melting point followed by cooling to form particles thermally, substituting mechanical action with thermal phase transition to achieve better particle morphology.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If thermoplastic polyester is processed at high shear rates above melting point to form melt emulsion, then spherical particle shape and narrow size distribution are achieved, but process complexity increases

Engineering Contradiction:

Improveparticle shape regularity and size distributionVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention controls particle morphology by changing key processing parameters: heating temperature above the melting point, cooling temperature below the melting point, and shear rate during mixing. By systematically controlling these parameters, the process achieves spherical particles with narrow size distribution while keeping the equipment and procedure relatively simple.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If powder particulates have irregular shapes and wide size distributions, then production cost is reduced, but packing efficiency deteriorates, resulting in extensive void formation in printed objects

Engineering Contradiction:

Improveproduction costVSAvoidpacking efficiency and void formation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

By utilizing the phase transition of thermoplastic polyester from solid to melt and back to solid, the invention naturally forms spherical particles with uniform sizes. This approach produces particles that pack efficiently with minimal voids, improving the reliability of printed objects without significantly increasing production cost, as the phase transition process is straightforward and uses common equipment.

Inventive Principle:

Principle #36Phase transitions

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 highly spherical thermoplastic polyester particles with improved flow properties and packing efficiency, reducing void formation and enhancing the structural integrity of 3-D printed objects.

Implementation Method 1

an inner phase that comprises a thermoplastic polyester at a temperature greater than a melting point or softening temperature of the thermoplastic polyester

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

cooling the melt emulsion to below the melting point or softening temperature of the thermoplastic polyester to form solidified particles

Methodology Applied

Scientific EffectFreezing: Freezing

Data Source

PatentUS20240026104A1Thermoplastic polyester particles and methods of production and uses thereof

Publication Date: 2024.01.25 XEROX CORP

AI summary

A method of producing thermoplastic particles may comprise: mixing a melt emulsion comprising (a) a continuous phase that comprises a carrier fluid having a polarity Hansen solubility parameter (dP) of about 7 MPa0.5 or less, (b) a dispersed phase that comprises a dispersing fluid having a dP of about 8 MPa0.5 or more, and (c) an inner phase that comprises a thermoplastic polyester at a temperature greater than a melting point or softening temperature of the thermoplastic polyester and at a shear rate sufficiently high to disperse the thermoplastic polyester in the dispersed phase; and cooling the melt emulsion to below the melting point or softening temperature of the thermoplastic polyester to form solidified particles comprising the thermoplastic polyester.