Ink Formulation for Stable Ejection and Image Density
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Solution Overview
Problem
Ink-jet recording technologies face challenges in maintaining stable ink ejection and image quality over time due to issues with ink viscosity and pigment dispersion, especially when exposed to high temperatures or when recording heads are left uncapped for extended periods, leading to clogging and offset problems.
Innovation Solution
The development of an ink formulation comprising water, a pigment dispersion, glycerin, 1,3-propanediol or 1,4-butanediol as humectants, and a C1-C4 monoalkyl ether of polyhydric alcohol as a penetrating agent, with specific mass content ratios to maintain ink stability and permeability, preventing viscosity changes and ensuring consistent image density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glycerin and 1,3-propanediol are used as humectants in ink-jet recording liquid, then stable ejection can be achieved, but ejection cannot be maintained in proper condition when recording heads stand without caps for long time
Solution Approach 1:
The patent changes the chemical composition parameters of the humectant system by introducing specific polyhydric alcohol monoalkyl ethers with controlled molecular weights and alkyl chain lengths. This modifies the ink's vapor pressure, hygroscopicity, and surface tension properties to achieve both stable ejection and long-term compositional stability when recording heads are stored uncapped.
Solution Approach 2:
The patent creates a composite humectant system combining glycerin, 1,3-propanediol, and polyhydric alcohol monoalkyl ethers in specific ratios. This composite formulation synergistically provides the moisture-retaining properties needed for stable ejection while the specific ether components prevent excessive viscosity increase during storage, maintaining both ejection reliability and composition stability.
2Speed
If water-based ink contains polyhydric alcohol monoalkyl ether with low vapor pressure, then ink penetration speed into recording media is enhanced, but viscosity and pigment dispersion are considerably changed after high-temperature exposure
Solution Approach 1:
The patent carefully selects polyhydric alcohol monoalkyl ethers with specific molecular weights and alkyl chain lengths to optimize the balance between penetration speed and thermal stability. The controlled vapor pressure and hydrophobicity of these ethers enable rapid ink penetration into recording media while their molecular structure resists degradation under high-temperature conditions, maintaining consistent viscosity and pigment dispersion.
3Productivity
If recording speed is increased, then image forming speed is improved, but nozzle clogging occurs due to unstable ink ejection
Solution Approach 1:
The patent modifies the ink's rheological parameters by incorporating polyhydric alcohol monoalkyl ethers that maintain optimal viscosity and surface tension across a range of temperatures and flow rates. This enables the ink to be ejected stably at high speeds while preventing nozzle clogging through controlled fluid dynamics properties.
Data Source
AI summary
An ink for ink-jet recording apparatuses includes water, a pigment dispersion, a humectant, and a penetrating agent. The ink includes glycerin of from 5% to 9% by mass and 1,3 -propanediol and/or 1,4-butanediol of from 30% to 45% by mass as the humectant. The ink also includes a C1-C4 monoalkyl ether of polyhydric alcohol of from 2.0% to 4.5% by mass as the penetrating agent.