Ink Set Ion Control for Nozzle Clogging and Color Developability
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Solution Overview
Problem
Existing ink jet recording technologies face challenges with pigment and dye ink agglomeration, leading to nozzle clogging and reduced color developability, especially when used together in low-cost, highly integrated ink jet recording apparatuses, where ion concentration limitations affect water solubility and clogging recoverability.
Innovation Solution
An aqueous ink set with a pigment ink containing divalent metal ions at 10 ppm or more and a dye ink with a potassium ion concentration of 50 ppm or less, along with increased lithium and sodium ions, is used to suppress pigment agglomeration, enhance color developability, and improve clogging recoverability, allowing for a simpler maintenance unit and reduced apparatus size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pigment ink and dye ink are mixed in the nozzle, then the recording quality improves, but pigment agglomeration occurs causing nozzle clogging
Solution Approach 1:
The patent changes the chemical parameters of the ink composition by controlling counter ion concentrations. Specifically, it limits potassium ions to 50 ppm or less and controls divalent metal ions to 10 ppm or less, while adjusting lithium and sodium ion concentrations to prevent pigment agglomeration when pigment ink and dye ink mix in the nozzle, thereby maintaining both recording quality and preventing nozzle clogging
Solution Approach 2:
The patent introduces specific counter ions (lithium ions, sodium ions) as intermediaries to mediate the interaction between pigment and dye. These ions act as protective agents that prevent the harmful agglomeration reaction while allowing the beneficial mixing for color development, thus resolving the contradiction between mixing benefits and clogging risks
2Reliability
If ion concentration is limited to prevent agglomeration, then nozzle clogging is reduced, but color developability deteriorates
Solution Approach 1:
The patent optimizes the parameter balance by setting specific concentration ranges: potassium ions ≤50 ppm, divalent metal ions ≤10 ppm, while increasing lithium ions to 600-2000 ppm and sodium ions to 1000-3000 ppm. This parameter configuration prevents agglomeration while maintaining sufficient ion strength for color developability
Solution Approach 2:
The patent creates a composite ion system combining multiple counter ions (lithium, sodium, potassium, and divalent metal ions) with complementary functions. Lithium and sodium ions primarily prevent agglomeration, while the composite system collectively maintains color developability, achieving both objectives through synergistic ion combinations
3Reliability
If separate maintenance units are provided for pigment ink and dye ink, then agglomeration is prevented, but device complexity and cost increase
Solution Approach 1:
The patent enables the ink system to self-prevent agglomeration through its chemical composition design. The controlled counter ion concentrations create a self-protective mechanism that prevents pigment agglomeration even when pigment ink and dye ink contact in the nozzle or on the maintenance unit, eliminating the need for separate maintenance units for each ink type
Solution Approach 2:
The patent creates a universal ink formulation that can be used together in a shared maintenance unit. By controlling counter ion concentrations, the patent makes both pigment ink and dye ink compatible with the same cleaning and maintenance system, allowing one maintenance unit to serve multiple ink types without causing agglomeration
Data Source
AI summary
An aqueous ink set for ink jet recording includes an aqueous pigment ink containing water and a pigment as a coloring agent and an aqueous dye ink containing water and a dye as a coloring agent, in which the concentration of the divalent metal ions of the pigment ink is 10 ppm or more, and the potassium ion concentration of the dye ink is 50 ppm or less.