Stereolithography Matte Surface Finish via Dual Cure Resin
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Solution Overview
Problem
Dual cure resins used in additive manufacturing often result in a glossy surface finish due to excess resin removal methods, which can be undesirable for consumer products, especially those contacting skin or clothing.
Innovation Solution
A method involving stereolithographic production using dual cure resins, where excess resin is partially removed and a thin film is partially cured with a second light of shorter peak wavelength, followed by further curing through heating or microwave irradiation to achieve a matte surface finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If excess resin is removed by washing techniques, then the object is cleaned of unpolymerized resin, but the surface becomes glossy which is perceived as inferior
Solution Approach 1:
The patent applies preliminary action by partially curing the thin film of unpolymerized resin on the object surface before final curing. This preliminary partial curing step modifies the surface properties in advance, creating a matte finish that persists through subsequent handling and final curing processes, thereby preventing the glossy finish problem before it occurs
Solution Approach 2:
The patent changes the chemical and physical parameters of the resin film by exposing it to specific wavelengths of light (405 nm or 355 nm) that initiate partial polymerization. This parameter change transforms the resin from a liquid state that produces glossy surfaces to a partially cured state that yields matte surfaces, fundamentally altering the surface finish characteristics
2Stability of the object's composition
If wiping or spinning techniques are used to clean excess resin, then washing-related chemistry alteration is avoided, but a film remains on the object that imparts glossy finish
Solution Approach 1:
The patent applies the extraction principle by selectively removing excess unpolymerized resin from the object surface through washing or other separation techniques, while deliberately leaving a controlled thin film. This selective extraction allows the object to be cleaned of bulk excess resin (maintaining composition stability) while retaining enough film material to create the desired matte surface finish after partial curing
Solution Approach 2:
The patent applies local quality by treating only the surface region of the object differently from the bulk. The thin film of unpolymerized resin on the surface is partially cured using specific wavelengths (405 nm or 355 nm), creating a localized matte finish layer while the bulk object undergoes normal curing. This local treatment achieves the matte surface without compromising the overall object properties
3Object-generated harmful factors
If a thin film of unpolymerized resin is left on the surface, then matte finish can be achieved through partial curing, but the object retains excess resin that needs separation
Solution Approach 1:
The patent applies partial action by performing an incomplete separation of excess resin - not removing all unpolymerized resin, but rather separating the bulk excess while deliberately retaining a thin controlled film on the surface. This partial separation achieves the dual benefit of cleaning the object sufficiently while maintaining enough surface resin to create the matte finish through subsequent partial curing
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 effectively transforms the glossy surface finish into a matte finish, addressing consumer preferences and performance issues for products made from dual cure resins.
Implementation Method 1
stereolithographically producing an intermediate object by polymerization of a dual cure resin with a first light having a first peak wavelength
Implementation Method 2
partially curing said thin film by exposing said thin film to a second light at a second peak wavelength
Implementation Method 3
further curing said intermediate object by heating, microwave irradiating, or both heating and microwave irradiating
Data Source
AI summary
Provided herein is a method of making an object having a matte surface finish by stereolithography. The method may include: (a) stereolithographically producing an intermediate object by polymerization of a dual cure resin with a first light having a first peak wavelength, the object having excess unpolymerized resin retained on the surface thereof; (b) separating a portion of said excess unpolymerized resin from said object while leaving a thin film of unpolymerized resin on the surface thereof; (c) partially curing said thin film by exposing said thin film to a second light at a second peak wavelength; and then (d) further curing said intermediate object by heating, microwave irradiating, or both heating and microwave irradiating, to produce an object having a matte surface finish.