Ink Formulation for High-Speed Inkjet Offset Control
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Solution Overview
Problem
Inkjet recording apparatuses face challenges in achieving high image forming speed without compromising image quality, as high-speed operation can lead to ink offset on the recording medium, resulting in poor imaging, and reducing ink ejection amount complicates achieving desired image density.
Innovation Solution
The development of an ink formulation containing water, a pigment dispersion with specific resin and carbon black characteristics, and a surfactant expressed by a general formula that improves permeability and viscosity control, ensuring effective ink penetration and stable ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ejection amount of ink is reduced to suppress offset, then the risk of poor imaging from offset is suppressed, but it becomes difficult to form images having a desired density
Solution Approach 1:
The patent changes the chemical composition parameters of the ink by introducing a specific surfactant (compound of formula I with specific molecular weight and structure) and controlling the resin molecular weight (10,000-40,000) and carbon black DBP oil absorption (40-80 g/100 g). These parameter changes improve ink permeability into the recording medium, allowing adequate ink penetration even at reduced ejection amounts, thus maintaining both low offset and desired image density
Solution Approach 2:
The surfactant acts as an intermediary substance that mediates between the ink and recording medium. It enhances the permeability of ink into the recording medium through its specific molecular structure (ethylene oxide and propylene oxide units), enabling the ink to penetrate effectively without requiring high ejection amounts, thereby preventing offset while maintaining image density
2Productivity
If the image forming speed is increased, then the productivity is improved, but the recording medium may be passed between ejection rollers causing ink offset
Solution Approach 1:
The patent modifies the ink's physical and chemical parameters, specifically controlling the dried-by-evaporation viscosity V40 to 50 mPa·s or less and adjusting the surfactant composition. These parameter changes enhance the ink's permeability and reduce its adhesion to ejection rollers, allowing high-speed image formation without offset while maintaining image quality
Solution Approach 2:
The patent converts the potential harmful effect of high-speed operation (which causes offset) into a beneficial situation by using the specific surfactant to control ink flow and penetration characteristics. The surfactant's molecular structure (with ethylene oxide and propylene oxide units) creates a balance where ink permeates effectively into the recording medium quickly, preventing offset even at high ejection speeds
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 formulation ensures good ejection from the inkjet head for a long period while maintaining desired image density, reducing the risk of offset and improving image quality at high-speed operations.
Implementation Method 1
a surfactant that includes a compound expressed by the general formula (I) below... compounds which can be contained in an ink to improve permeability of the ink into a recording medium
Implementation Method 2
The mass average molecular weight of the resin is from 10,000 to 40,000... The dried-by-evaporation viscosity V40 of the ink is 50 mPa·s or less
Implementation Method 3
water, a pigment dispersion, and a surfactant... dried-by-evaporation viscosity V40 of the ink
Data Source
AI summary
An ink for ink jet recording apparatuses contains water and a pigment dispersion containing a resin and carbon black. The ink additionally contains a surfactant including a compound expressed by the general formula (I) below, and the mass average molecular weight of the resin, the DBP oil absorption of the carbon black, the content of the resin with respect to the content of the carbon black in the pigment dispersion, and the dried-by-evaporation viscosity V40, which is the viscosity of the ink at the dryness of 40% by mass, are all within the respective predetermined ranges.