Inkjet Ink Hiding Layer Coating Agent Dispersion Stability
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Solution Overview
Problem
Inkjet inks with high hiding properties often suffer from poor dispersion stability due to settling of large, high-specific-gravity white pigments like titanium oxide, and conventional recording sheets with hiding layers can only produce flat, planar images, lacking the ability for novel expressions.
Innovation Solution
An inkjet ink comprising radical polymerizable components, including a high Tg polyfunctional monomer and a monofunctional monomer, with a volatile solvent, which undergoes radical polymerization to form a three-dimensional network structure, providing hiding properties equivalent to titanium oxide without using it, and a hiding layer coating agent for recording sheets that allows for novel image expressions by controlling light diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If titanium oxide or other white pigments with high hiding power are used in inkjet ink, then the hiding property and coloring power are improved, but the dispersion stability deteriorates due to easy settling caused by large specific gravity
Solution Approach 1:
The invention extracts and removes titanium oxide and other conventional white pigments from the inkjet ink composition. Instead of using these settling-prone pigments, the patent employs a hiding layer coating applied to the recording sheet surface, which provides the necessary hiding power without compromising ink dispersion stability.
Solution Approach 2:
The invention introduces a hiding layer as an intermediary element between the inkjet ink and the recording sheet. This hiding layer, containing white pigment and binder, is applied to the sheet surface and provides the hiding power that would otherwise require high concentrations of settling-prone pigments in the ink itself.
2Illumination intensity
If conventional hiding layers with inorganic filler are used to enhance color development, then the hiding property is improved, but the image expression becomes limited to flat and planar only
Solution Approach 1:
The invention applies local quality by creating hiding layers with varying properties in different regions. The hiding layer can have different optical characteristics, thicknesses, or compositions in different areas, enabling diverse image expressions such as transparent, translucent, or opaque regions, rather than uniform flat appearance.
Solution Approach 2:
The invention introduces dynamics to the hiding layer system, allowing it to respond to different inkjet inks or processing conditions. The hiding layer can exhibit variable transparency or optical properties based on the applied ink composition, enabling flexible image expression and novel visual effects.
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 inkjet ink achieves enhanced dispersion stability and hiding properties without titanium oxide, enabling flexible and durable prints with improved followability and abrasion resistance, while the recording sheet allows for novel image expressions by controlling light interaction.
Implementation Method 1
the radical polymerizable components undergo a radical polymerization reaction due to a function of the photo-radical polymerization initiator
Implementation Method 2
the volatile solvent volatilizes to porosify the cured product and therefore, diffuse reflection of light occurs inside the cured product
Data Source
AI summary
The present invention provides an inkjet ink and a hiding layer coating agent that contain radical polymerizable components including a polyfunctional monomer that includes a high Tg polyfunctional monomer with a glass transition temperature Tg of not less than 40° C. at a ratio of not less than 30 mass % and a monofunctional monomer, a volatile solvent, and a photo-radical polymerization initiator, with a ratio of the monofunctional monomer being 5 to 70 mass % in the radical polymerizable components and a ratio of the volatile solvent being 50 to 400 mass % with respect to the radical polymerizable components and are excellent in dispersion stability due to not containing (excluding) a white pigment such as titanium oxide, etc., and enable printing of a white or colored character having a high hiding property equivalent to that in a case where the white pigment is contained.