Inkjet 3D Printing Color Control via Layered Curable Compositions

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Solution Overview

Problem

Existing three-dimensional object production methods, particularly in additive manufacturing, struggle to achieve accurate color gradations and transparency in material-jetted objects, limiting their application in creating detailed and aesthetically pleasing items like artificial teeth.

Innovation Solution

A method using a combination of curable compositions A and B, where composition A is white and composition B is transparent, with composition C containing coloring materials, is discharged and cured using an inkjet method to produce a three-dimensional object with controlled total light transmittance, allowing for precise expression of color gradations and transparency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If coloring ink amount is varied to minimize color unevenness, then color tone uniformity is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvecolor tone uniformityVSAvoidmanufacturing complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the coloring process into multiple discrete coloring ink layers (first coloring ink, second coloring ink, third coloring ink) applied at different stages of layer lamination. Each coloring ink targets specific regions where color accumulation occurs, allowing precise control of color tone uniformity without requiring complex real-time adjustment mechanisms.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies coloring inks in advance during the layer lamination process rather than as a post-processing step. By discharging coloring inks at predetermined positions in each layer before final curing, the method preemptively corrects color unevenness that would otherwise require complex post-manufacturing adjustments.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If deposited region of coloring material is reduced, then color precision is improved, but surface area coverage decreases

Engineering Contradiction:
Improvecolor precisionVSAvoidsurface area coverage
Core Design Contradiction:
Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The patent applies different coloring inks to different local regions of the three-dimensional object based on where color accumulation occurs during layer lamination. The first coloring ink targets overlapping regions, the second coloring ink targets specific intermediate regions, and the third coloring ink targets other specific regions, providing localized color control without requiring uniform coverage of the entire surface.

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

This approach enables the production of highly accurate, colored three-dimensional objects with excellent printing accuracy and strength, suitable for applications such as artificial teeth, by ensuring the deposited region of the coloring material is smaller than the base deposited region, thereby improving visibility and durability.

Implementation Method 1

discharging a curable composition A and a curable composition B by use of an inkjet head to form a base deposited region

Methodology Applied
Scientific EffectInkjet deposition:

Implementation Method 2

irradiating the base deposited region with an irradiation source to cure the curable composition A and the curable composition B

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP4249214B1Three-dimensional object producing method, three-dimensional object producing apparatus, and artificial tooth object producing method
Publication Date: 2024.10.30 RICOH CO LTD
  • EP4249214B1 patent drawingFigure 1~2
  • EP4249214B1 patent drawingFigure 3~4
  • EP4249214B1 patent drawingFigure 5~6

AI summary

A three-dimensional object producing method for producing a three-dimensional object using a curable composition A and a curable composition B, and using a curable composition C is provided. The method includes discharging either or both of the curable compositions A and B by an inkjet method and curing either or both of them, to produce a base cured product, and discharging the curable composition C containing a coloring material by an inkjet method and curing the curable composition C, to produce a cured product C. A deposited region (D1) formed by deposition of the curable composition C discharged is smaller than a base deposited region (D2) formed by deposition of the curable compositions A and B discharged. An absolute value of a total light transmittance difference between a cured product A of the curable composition A and a cured product B of the curable composition B is 10% or greater.