Ink Jet Recording Apparatus Ink Formulation for Optical Density Stability
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Solution Overview
Problem
Ink jet recording apparatuses with large capacity ink storage portions and openable ink inlet ports face issues with maintaining optical density at the edges of black images adjacent to color images over long periods, due to pigment settlement and concentration gradients, leading to decreased image quality.
Innovation Solution
The use of a black ink containing carbon black and an acrylic resin particle, with the mass content of carbon black in the black ink being less than or equal to the mass content of organic pigment in the color ink, helps mitigate pigment settlement and agglomeration, thereby maintaining optical density by ensuring the ink's properties satisfy specific relationships and particle distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large capacity main tank with an openable ink inlet port is used for high productivity, then ink storage capacity is improved, but pigment settlement and concentration gradients occur leading to decreased optical density at image edges
Solution Approach 1:
The patent changes the physical-chemical parameters of the ink by introducing a specific binder resin with controlled molecular weight (10,000-100,000) and functional groups. This modifies the ink's rheological properties to prevent pigment settlement while maintaining high storage capacity, thus resolving the contradiction between productivity and optical density uniformity
Solution Approach 2:
The patent creates a composite ink system combining carbon black or organic pigments with a specifically designed binder resin. This composite formulation ensures stable pigment suspension and prevents concentration gradients in large capacity tanks, maintaining optical density uniformity while enabling high productivity
2Adaptability or versatility
If the ink inlet port is opened for ink injection, then refilling capability is improved, but pigment adhesion to the recording head occurs after long period recording
Solution Approach 1:
The binder resin acts as an intermediary between the pigment particles and the recording head surface. The specifically designed resin with controlled molecular weight and functional groups prevents direct adhesion of pigment particles to the recording head, thereby maintaining reliability while allowing refilling capability
3Illumination intensity
If black ink with high carbon black content is used for excellent color developability, then image quality is improved, but optical density decrease at image edges occurs more rapidly
Solution Approach 1:
The patent optimizes the molecular weight parameter of the binder resin (10,000-100,000) to achieve the right balance between pigment dispersion for color developability and pigment suspension stability over time. This parameter control allows high carbon black content while preventing rapid optical density decrease
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
This configuration effectively suppresses the decrease in optical density at the edge of black images adjacent to color images, ensuring high-quality image recording over extended periods without pigment adhesion issues in the recording head.
Implementation Method 1
the aqueous ink includes a black ink containing a carbon black and an acrylic resin particle... effectively suppresses the decrease in optical density at the edge of black images adjacent to color images... without pigment adhesion issues in the recording head
Data Source
AI summary
An ink jet recording method is provided that can record high quality images over a long period of time while suppressing a decrease in optical density at the edge of a black image adjacent to a color image, even in the case where an ink jet recording apparatus having a large capacity ink storage portion having an openable and closable ink inlet port is used. The method is an ink jet recording method including, using an ink jet recording apparatus having a first ink storage portion, a second ink storage portion and a recording head that ejects an aqueous ink, recording an image. The aqueous ink includes a black ink, and a color ink containing an organic pigment, and the content P1 of the carbon black in the black ink and the content P2 of the organic pigment in the color ink satisfy P1≤P2.