TPU Coating Process for Smoother 3D-Printed Surfaces
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Solution Overview
Problem
Existing additive manufacturing methods using thermoplastic polyurethane powders result in objects with rough, porous surfaces that are prone to contamination, moisture absorption, and reduced mechanical properties, and conventional treatments like polishing and solvent corrosion can alter the object's geometry or are environmentally harmful.
Innovation Solution
A method involving contact with an aqueous polyurethane dispersion and water-dispersible polyisocyanate at controlled pressure and temperature conditions to enhance penetration and chemical reaction, forming a uniform film that improves surface smoothness and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If polishing is used to smooth the surface, then surface roughness is reduced, but the geometry of the object is changed due to material abrasion
Solution Approach 1:
The patent replaces mechanical polishing with a chemical treatment process using aqueous polyurethane dispersion and water-dispersible polyisocyanate. The chemical reaction forms a uniform film on the surface without mechanical abrasion, thereby smoothing the surface while preserving the original geometry and dimensions of the object.
Solution Approach 2:
The patent changes the physical and chemical parameters of the surface treatment by using controlled pressure (100-800 mbar) and temperature (70-90°C) conditions during the chemical reaction process. These parameter controls enable uniform film formation without excessive material removal, maintaining geometric accuracy while achieving surface smoothness.
2Shape
If organic solvent corrosion is used to eliminate porosity, then surface smoothness is improved, but the geometry of the object is altered and environmental protection is compromised
Solution Approach 1:
The patent changes the chemical composition parameters by replacing organic solvents with aqueous polyurethane dispersion containing 36-70% solid constituent. The treatment conditions (pressure: 100-800 mbar, temperature: 70-90°C) are optimized to achieve uniform film formation without the harmful effects of organic solvents, eliminating porosity while maintaining environmental safety and geometric integrity.
Solution Approach 2:
The patent uses water as the solvent base instead of persistent organic solvents like DMF. Water is environmentally friendly, easily removable, and does not require high-temperature vacuum evacuation, thereby eliminating the environmental harm associated with organic solvent corrosion while achieving the same surface improvement.
3Reliability
If the object is left at controlled pressure and temperature for extended time, then penetration and chemical reaction are enhanced, but production time is increased
Solution Approach 1:
The patent optimizes the treatment parameters to achieve the best balance between coating quality and production time. By controlling pressure (100-800 mbar) and temperature (70-90°C), the chemical reaction proceeds efficiently to form a uniform film within 3-10 minutes, enhancing penetration and reaction without requiring excessively long processing times.
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 results in objects with enhanced tensile strength, elongation, and surface appearance, while being environmentally friendly, by using an aqueous treatment that penetrates and reacts to improve mechanical properties without altering the object's geometry.
Implementation Method 1
contact with an aqueous polyurethane dispersion and water-dispersible polyisocyanate at controlled pressure and temperature conditions to enhance penetration and chemical reaction, forming a uniform film
Implementation Method 2
leaving the object at 10° C.-30° C. and 100 mbar-800 mbar for 3-10 minutes
Implementation Method 3
heat-treating the object at a temperature of 70° C.-90° C. after returning to normal pressure
Data Source
AI summary
The present invention relates to a method for producing an at least partially coated object and to an at least partially coated object obtained by the method. The method comprises bringing the object completely or partly into contact with a treating agent; leaving the object at 10° C.-30° C. and 100 mbar-800 mbar for 3-10 minutes; and heat-treating the object at a temperature of 70° C.-90° C. after returning to normal pressure; wherein the object is produced from a construction material by means of an additive manufacturing method, and the construction material comprises a thermoplastic polyurethane; and wherein the treating agent comprises an aqueous polyurethane dispersion and a water-dispersible polyisocyanate, and the viscosity of the treating agent is 100 mPa·s-550 mPa·s, measured under the condition of spindle L 2/30 rpm according to standard DIN 53019; and wherein the amount of the solid constituent of the aqueous polyurethane dispersion is 36% by weight to 70% by weight, and the amount of the solid constituent of the water-dispersible polyisocyanate is 4% by weight to 8% by weight, relative to the total weight of the treating agent, wherein the terms “normal pressure” and “solid constituent” are defined as specified in the description. The at least partially coated object of the present invention has good mechanical properties and good surface effect.