Inkjet Ink Set Acid Value Differentiation Prevents Color Spreading
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Solution Overview
Problem
Existing inkjet recording technologies face challenges in achieving simultaneous ejection stability, storage stability, and image density while preventing color-spreading when using black and color pigment inks together.
Innovation Solution
An inkjet recording ink set comprising a black pigment ink with a specific anionic self-emulsifying ether polyurethane resin and color pigment inks with a compound represented by General Formula (1), where the acid value of the polyurethane resin in the black ink is between 65 mgKOH/g to 85 mgKOH/g, and in the color ink is 10 mgKOH/g to 40 mgKOH/g lower, along with a dispersing agent like sodium naphthalene sulfonate formaldehyde condensate, to prevent color-spreading and ensure stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If black pigment ink and color pigment ink are used separately with optimized formulations, then image density and ejection stability are improved, but color-spreading occurs when they are ejected simultaneously
Solution Approach 1:
The patent applies local quality by using different polyurethane resin formulations with different acid values for black and color inks. The black ink contains a polyurethane resin with acid value of 50-90 mgKOH/g, while the color ink contains a polyurethane resin with acid value of 30-70 mgKOH/g. This localized differentiation in chemical properties allows each ink to maintain its individual performance characteristics while preventing color-spreading when used together.
2Reliability
If black pigment ink and color pigment ink are formulated for optimal individual performance, then storage stability and ejection stability are achieved, but color-spreading cannot be prevented when ejected simultaneously
Solution Approach 1:
The patent applies parameter changes by carefully controlling the acid value parameter of the polyurethane resin in each ink type. The black ink uses a polyurethane resin with acid value of 50-90 mgKOH/g, while the color ink uses a polyurethane resin with acid value of 30-70 mgKOH/g. This parameter differentiation creates compatible ink formulations that maintain storage stability individually and prevent color-spreading when used together in the same printing system.
3Object-generated harmful factors
If black pigment ink and color pigment ink are formulated with different polyurethane resins, then color-spreading is prevented, but formulation complexity increases
Solution Approach 1:
The patent manages formulation complexity by focusing on a single key parameter - the acid value of the polyurethane resin. Rather than changing multiple formulation components, the invention maintains the same base polyurethane resin type for both black and color inks but adjusts the acid value within specific ranges. This simplifies the overall formulation process while effectively preventing color-spreading.
Data Source
Figure 1
AI summary
An inkjet recording ink set containing at least a black pigment ink and a color pigment ink which has a color selected from one or more colors, wherein the black pigment ink contains a first anionic self-emulsifying ether polyurethane resin having an acid value of 65 mgKOH/g to 85 mgKOH/g, and the at least one color pigment ink of every color contains a second anionic self-emulsifying ether polyurethane resin having an acid value 10 mgKOH/g to 40 mgKOH/g lower than those of the first anionic self-emulsifying ether polyurethane resin contained in the black pigment ink.