Photocurable Acrylate Coating for 3D Printed Surface Haze Reduction

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Solution Overview

Problem

Additive manufacturing techniques often result in three-dimensional printed articles with surface haze and reduced optical clarity due to surface roughness and poor miscibility of cationically curable and free radically curable compounds, leading to limited improvement in light transmittance even with existing polishing and coating methods.

Innovation Solution

Applying a photocurable acrylate composition comprising an aliphatic polyether urethane acrylate component, (meth)acrylate ester reactive monomer, photoinitiator, and optional reactive diluent and adhesion promoter to the surface of three-dimensional printed articles, and curing it with radiation to form a light-transmitting coating, which increases light transmittance without coloring the article.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If polishing surfaces using sandpaper and buffing is used to reduce surface roughness, then surface smoothness is improved, but the degree of improvement in optical clarity is limited and difficult-to-access surfaces remain challenging

Engineering Contradiction:

Improvesurface smoothnessVSAvoidaccessibility to difficult surfaces

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces mechanical polishing methods (sandpaper, buffing) with a chemical/photocurable coating system. The coating is applied via spray or dip methods that automatically reach all surface areas including narrow channels and difficult-to-access regions, then cured photographically to create a smooth, optically clear surface without manual intervention.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a transparent photocurable coating as an intermediary layer between the rough 3D printed surface and the external environment. This coating fills surface irregularities and provides a smooth optical interface, mediating the contradiction between maintaining the original 3D printed structure and achieving high optical clarity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Illumination intensity

If existing transparent coatings are applied to improve transmittance, then light transmittance is improved, but colouration of the article occurs

Engineering Contradiction:

Improvelight transmittanceVSAvoidcolouration

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The patent carefully selects and controls the chemical composition parameters of the photocurable coating, specifically using transparent acrylate monomers and oligomers with high light transmittance and no colorants. The photoinitiator system is also selected to cure without yellowing, maintaining optical clarity while achieving the desired transmittance improvement.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite coating formulation comprising multiple components: transparent acrylate monomers, oligomers, photoinitiators, and optional adhesion promoters. This composite material system achieves both high light transmittance and colorlessness by combining materials with complementary properties, avoiding the coloration issues of single-component coatings.

Inventive Principle:

Principle #40Composite materials

3Strength

If cationically curable and free radically curable compounds are used in hybrid compositions, then mechanical properties are improved, but miscibility is poor leading to haziness

Engineering Contradiction:

Improvemechanical propertiesVSAvoidmiscibility

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent applies different curable compound types in localized regions or layers within the coating system. The primer layer may use one curing mechanism optimized for adhesion, while topcoats use another curing mechanism optimized for optical clarity and transmittance. This local differentiation allows each layer to perform its specific function without the miscibility issues of hybrid compositions.

Inventive Principle:

Principle #3Local quality

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 process significantly enhances light transmittance through the coated articles by 10% to 90% or more across the visible spectrum, compared to uncoated articles, while maintaining transparency without coloration.

Implementation Method 1

curing the photocurable acrylate composition by exposure to radiation in the electromagnetic spectrum to form on the three-dimensional printed article a light transmitting coating

Methodology Applied

Scientific EffectPhotopolymerisation: Photopolymerisation

Data Source

PatentUS12084591B2Three-dimensional articles made by additive manufacturing having reduced surface haze

Publication Date: 2024.09.10 HENKEL KGAA

AI summary

Methods for manufacturing three-dimensional articles having reduced surface haze, by applying a coating to the surface of a three-dimensional article made by additive manufacturing are described.