Inkjet Ink Segmented Pigment Dispersion for Bleeding Control
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Solution Overview
Problem
Current inkjet recording technologies face challenges in achieving high image density, color saturation, and abrasion resistance while preventing color bleeding on common recording media like plain paper, as existing dispersion systems and pretreatment liquids often compromise on one or more of these factors.
Innovation Solution
An inkjet recording ink formulation containing dispersed organic pigment particles, polymer-coated organic pigment particles, and a surfactant to reduce surface tension, combined with a pretreatment liquid using a coagulating agent like lactic acid or polyvalent metal salts, which enhances ink penetration and fixation on the recording medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resin emulsion is added to improve abrasion resistance and water resistance, then storage stability is improved, but viscosity increases which requires reducing pigment concentration (jeopardizing image density and color saturation) or reducing wetting agent amount (jeopardizing jetting stability)
Solution Approach 1:
The ink formulation is segmented into two distinct pigment dispersion systems: (1) pigment particles dispersed with anionic surfactant/polymer dispersing agent, and (2) polymer-coated pigment particles dispersed with nonionic surfactant. This segmentation allows each system to contribute different properties - the first providing color strength and the second providing abrasion resistance and water resistance - without the negative viscosity effects of a single high-concentration resin emulsion system.
Solution Approach 2:
The invention creates a composite dispersion system combining two types of pigment particles with different surface treatments and dispersing mechanisms. The anionic surfactant-dispersed pigment particles and nonionic surfactant-dispersed polymer-coated pigment particles work synergistically to achieve high image density, color saturation, and durability simultaneously, resolving the contradiction between pigment concentration and storage stability.
2Object-generated harmful factors
If cationic particles or polyvalent metal salts are used as coagulating agents in pretreatment liquid, then aggregation speed is fast which suppresses color bleeding, but image density and color saturation become low and abrasion resistance deteriorates
Solution Approach 1:
The invention applies preliminary action by using the nonionic surfactant-dispersed polymer-coated pigment particles to form a stable base layer on the recording medium before the anionic surfactant-dispersed pigment particles are applied. This preliminary layer provides abrasion resistance and water resistance, allowing the subsequent color-forming particles to penetrate and aggregate effectively without being lost, thus achieving high image density and color saturation while maintaining durability.
Solution Approach 2:
The polymer-coated pigment particles act as an intermediary between the pretreatment liquid coagulating agent and the main pigment particles. The polymer coating provides a controlled aggregation mechanism that is less aggressive than direct cationic particle or polyvalent metal salt action, preventing excessive dot shrinkage while still achieving color bleeding suppression. This intermediary layer allows pigment particles to penetrate the recording medium more effectively, improving image density and color saturation.
3Quantity of substance
If pigment concentration is increased to improve image density and color saturation, then coloring ability is improved, but viscosity increases which requires reducing wetting agent amount (jeopardizing jetting stability)
Solution Approach 1:
The ink is segmented into two pigment dispersion systems with different surfactant requirements. The anionic surfactant-dispersed pigment particles contribute to color strength, while the nonionic surfactant-dispersed polymer-coated pigment particles contribute to durability and help control viscosity. This segmentation allows high total pigment concentration to be achieved without excessive viscosity increase, as each system can be optimized independently for its specific function.
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 inkjet recording method produces images with excellent coloring ability, abrasion resistance, and prevents color bleeding, achieving high image density and saturation without compromising on the stability and quality of the printed images.
Implementation Method 1
a surfactant to decrease the surface tension of the ink
Implementation Method 2
a pretreatment liquid which aggregates a coloring material is applied to a recording medium in advance
Implementation Method 3
dispersed particles B are coloring particles obtained by dispersing a polymer-coated organic pigment in water
Data Source
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AI summary
An ink for inkjet recording, containing: dispersed particles A; dispersed particles B; a water-soluble solvent; a surfactant; and water, wherein the dispersed particles A are coloring particles obtained by dispersing an organic pigment in water with assistance of a surfactant, and the dispersed particles B are coloring particles obtained by dispersing a polymer-coated organic pigment in water.