3D Printing Internally Transparent Amorphous Thermoplastic Parts

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Solution Overview

Problem

Current 3D printing technologies face challenges in producing transparent parts with amorphous thermoplastic polymers, as material extrusion methods often result in hazy outputs due to layer interfaces, and existing materials like ABS and PETG exhibit limitations in transparency, mechanical properties, and printability.

Innovation Solution

The method involves selecting an amorphous thermoplastic polymer with a specific glass transition temperature (Tg) and optimizing printing conditions, such as build plate and chamber temperatures, to maintain the polymer at a temperature above its Tg for an extended period, allowing for inter-layer chain entanglement and reducing layer lines, thereby achieving high internal clarity and strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If material extrusion 3D printing is used to produce transparent parts, then the printing process is simple and fast, but the parts become hazy due to layer interfaces

Engineering Contradiction:
Improveprinting simplicityVSAvoidhaze from layer interfaces
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by maintaining the polymer above its glass transition temperature (Tg) for extended periods using heated build plates and chambers. This temperature parameter change enables polymer chain mobility that eliminates layer interfaces and achieves internal transparency while preserving the simplicity of material extrusion printing

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements preliminary action by pre-heating the build plate and chamber to temperatures above the polymer's Tg before printing. This preliminary thermal preparation ensures that when the polymer is deposited, it immediately enters a state conducive to chain entanglement and interface elimination, preventing haze formation from the outset

Inventive Principle:
Principle #10Preliminary action

2Productivity

If thicker layer heights are used to reduce print time, then productivity increases, but internal transparency is lost

Engineering Contradiction:
Improveprint speedVSAvoidloss of internal clarity
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent resolves this contradiction by changing the temperature parameter to remain above Tg for extended periods using heated build plates and chambers. This allows thicker layers (0.1mm or greater) to be printed at high speeds while maintaining internal transparency through sustained polymer chain mobility and entanglement

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies continuity of useful action by maintaining the polymer in a mobile, high-temperature state throughout the entire printing process. The heated build plate and chamber continuously supply heat to keep the polymer above Tg, ensuring that even thick layers deposited at high speeds achieve complete chain entanglement and internal transparency without interruption

Inventive Principle:
Principle #20Continuity of useful action

3Productivity

If printing speed is increased to reduce production time, then productivity improves, but layer lines and haze increase

Engineering Contradiction:
Improveextrusion speedVSAvoidlayer lines and haze
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent resolves this contradiction by changing the temperature parameter to remain above Tg for extended periods using heated build plates and chambers. This thermal parameter change provides sufficient time for chain entanglement even at high extrusion speeds, eliminating layer lines and haze while maintaining productivity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements continuity of useful action by maintaining continuous heating above Tg throughout the printing process. The heated build plate and chamber continuously supply thermal energy that enables rapid chain entanglement, allowing high-speed printing without sacrificing transparency or increasing layer line visibility

Inventive Principle:
Principle #20Continuity of useful action

4Object-generated harmful factors

If conventional acrylic polymers are used for transparency, then clarity is improved, but brittleness makes them impractical for extrusion printing

Engineering Contradiction:
Improveinternal clarityVSAvoidprintability
Core Design Contradiction:
Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The patent applies composite materials by combining acrylic polymer (for clarity) with flexible polymers or plasticizers (for brittleness reduction). This composite approach creates a material that maintains the optical properties of acrylic while gaining the ductility needed for successful material extrusion printing

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent resolves the printability issue by changing the temperature parameter to remain above Tg for extended periods using heated build plates and chambers. This thermal parameter change increases polymer chain mobility and reduces brittleness during printing, enabling successful extrusion of acrylic-based materials while maintaining their clarity

Inventive Principle:
Principle #35Parameter changes

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

This approach enables the production of internally transparent parts with haze levels below 5%, improving mechanical strength and reducing print time by allowing thicker layer heights and faster print speeds, while maintaining part clarity and accuracy.

Implementation Method 1

the polymer chains in each layer to be mobile and fluid, permitting sufficient inter-layer chain entanglements

Methodology Applied
Scientific EffectPolymer chain mobility: Viscoelasticity

Implementation Method 2

maintain the polymer at a temperature above its Tg for an extended period

Methodology Applied
Scientific EffectGlass transition temperature effect: Phase Change

Implementation Method 3

build plate and chamber temperatures, to maintain the polymer at a temperature above its Tg

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 4

provide an internal temperature of the composition... for at least 5 minutes, preferably at least 10 minutes

Methodology Applied
Scientific EffectThermal energy: Thermal Energy Storage

Data Source

PatentEP3946905B13D printing of internally transparent articles
Publication Date: 2024.08.28 ARKEMA FRANCE SA
  • EP3946905B1 patent drawingFigure 1~3
  • EP3946905B1 patent drawingFigure 4~5
  • EP3946905B1 patent drawingFigure 6~7

AI summary

The invention relates a material extrusion additive manufacturing method for producing a clear, internally transparent part composed of amorphous thermoplastic polymer layers at least 0.1 mm thick. The invention also relates to internally clear parts made by the method, having an internal haze of less than 25%, less than 15%, less than 10% and even less than 5%. The method creates a printed dot or line of amorphous thermoplastic polymer that remains at a high internal temperature for a long enough period of time to allow the polymer chains in each layer to be mobile and fluid, permitting sufficient inter-layer chain entanglements to reduce and eliminate layer lines. With a nearly 100% dense final part, voids are eliminated. The resultant printed article has a very high internal clarity, and can have a haze of less than 5%.