Metallic Ink Composition for Capillary Application
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Solution Overview
Problem
Conventional metallic inks used in capillary application devices tend to experience color pigment migration into absorbent paper bases, leading to fading or disappearance of colors, especially with blue pigments on black papers, and sedimentation issues that can block the capillary channels.
Innovation Solution
A metallic ink composition containing 30% to 80% water, 1% to 15% maleinate resin, 0.4% to 10% color pigments with particle size ≤ 6 µm, 1% to 15% metal pigments with grain size distribution D50 < 25 µm, 1% to 20% humectants, and 0.2% to 12% additives, including maleic acid-modified rosin resin and organophosphorus compounds, which improves pigment migration and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional metallic ink is used with capillary application devices, then the ink can be applied through fine capillary channels, but the color pigment particles migrate into the paper base causing fading or disappearance of color
Solution Approach 1:
A binder resin is introduced as an intermediary substance that selectively binds to color pigment particles while remaining compatible with the capillary application system. This binder acts as a mediator that holds the color pigment in place during application and prevents its migration into the paper base, while allowing the metallic particles to maintain their capillary flow properties
Solution Approach 2:
The ink formulation is transformed into a composite material system containing multiple particle types (metallic particles, color pigment particles, and binder resin) with carefully controlled size distributions and interactions. The composite structure allows different components to perform their specific functions: metallic particles provide flow through capillaries, while the binder-resin complex anchors color pigments to prevent migration
2Productivity
If color pigment particles are made small enough to pass through capillary channels, then they can be transported by the capillary effect, but they migrate more easily into the paper base
Solution Approach 1:
The binder resin serves as an intermediary that attaches to small color pigment particles (≤6 μm) enabling them to be transported through capillary channels while preventing their subsequent migration into the paper base. The binder acts as a protective intermediary layer that maintains transportability while blocking harmful migration
Solution Approach 2:
The size and properties of the binder resin particles are carefully controlled to be larger than the color pigment particles (binder ≥1 μm versus pigment ≤6 μm). This parameter differentiation ensures that the binder remains in the capillary system while the smaller pigment particles are held by the binder, preventing their migration into the paper
3Ease of manufacture
If metallic particles are added to provide metallic effect, then the desired aesthetic is achieved, but sedimentation occurs blocking the capillary channels
Solution Approach 1:
The metallic particles are engineered with specific size parameters (D50 <25 μm) and the binder resin is sized ≥1 μm to create a size hierarchy. This parameter control ensures metallic particles remain suspended in the ink matrix without settling, while the larger binder particles provide structural support to maintain channel patency
Solution Approach 2:
The ink forms a composite suspension where metallic particles, color pigments, and binder resin create a stable multi-phase system. The composite structure prevents sedimentation by distributing particle sizes and densities, ensuring metallic particles remain suspended while the overall formulation maintains capillary channel flow
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 ink composition significantly reduces color pigment migration and sedimentation, maintaining the original color intensity and preventing channel blockages, with the maleic resin and organophosphorus compounds enhancing dispersion stability and preventing fading.
Implementation Method 1
The capillary material, which consists, for example, of fibers or a sintered material, is traversed by a large number of extremely fine channels in which the ink is transported due to adhesion forces or the capillary effect.
Implementation Method 2
The crucial component of the ink in terms of improved migration behavior is the maleic resins present in dissolved form in the aqueous matrix. Due to the absence or at least reduced particle migration, the original color is retained
Implementation Method 3
A particularly long-lasting dispersion of the metal particles, in particular the preferably used aluminum particles, and the color pigments is achieved by adding an organophosphorus compound
Data Source
AI summary
Metallic ink, comprises: 30-80% of water; 0.4-10% of color pigments having a particle size of = 6 mu m; 1-15% of dissolved resin from the group consisting of maleate resin and/or maleic acid modified rosin; 1-15% of metallic pigments having a particle size distribution (D50) of less than 25 mu m; 1-20% of humectants; and 0.1-10% of additives; and having a viscosity of 5-10 mPa.s (Brookfield, CPE-40 spindle, 20 rpm). An independent claim is included for an applicator, comprising: a writing tip made of a capillary material; and an ink storage device (2) containing the capillary material and the metallic ink.