Inkjet Ink Formulation for Tablet Print Stability
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Solution Overview
Problem
Conventional inkjet inks face challenges in achieving a balance between drying properties, lightfastness, and discharge stability, often resulting in discoloration and fading of printed images, especially when used on tablets.
Innovation Solution
The development of an inkjet ink formulation that includes Red No. 102, reduced isomaltulose as a viscosity modifier, and a solvent mixture of water, monohydric alcohol (such as ethanol, NPA, or IPA), and a wetting agent (like glycerol and PG), optimized within specific mass ratios to enhance ink fixability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the content of drying solvents (lower alcohol) is increased to enhance drying properties, then drying properties are improved, but discharge stability deteriorates and colorant precipitation occurs
Solution Approach 1:
The patent changes the chemical composition parameters of the solvent system by introducing monohydric alcohol (ethanol, NPA, or IPA) in combination with lower alcohol and water, along with specific wetting agents. This parameter change allows the ink to achieve fast drying properties while preventing colorant precipitation and maintaining discharge stability through optimized solvent ratios and interactions.
Solution Approach 2:
The patent creates a composite solvent system combining multiple components: monohydric alcohol, lower alcohol, water, and wetting agents (glycerol and/or PG). This composite approach leverages the complementary properties of each component to achieve both fast drying and stable discharge, resolving the contradiction between drying speed and discharge reliability.
2Illumination intensity
If food dyes are used as colorants to increase visibility, then visibility is improved, but lightfastness deteriorates causing discoloration and fading
Solution Approach 1:
The patent introduces wetting agents (glycerol and/or propylene glycol PG) as intermediary substances that mediate between the food dye colorants and the solvent system. These wetting agents form protective interactions with the colorants, reducing their exposure to light-induced degradation while maintaining visibility, thus improving lightfastness without sacrificing color intensity.
Solution Approach 2:
The patent optimizes the concentration parameters of food dyes within specific ranges (0.5-3.0 mass% for Red No. 102) and adjusts the solvent composition ratios to achieve the best balance between visibility and lightfastness. This parameter optimization prevents colorant degradation while maintaining adequate visibility.
3Manufacturing precision
If viscosity modifiers (glycerol or thickeners) are added to improve printing characteristics, then ink droplet landing accuracy is improved, but drying properties deteriorate
Solution Approach 1:
The patent changes the viscosity modification approach by using reduced isomaltulose instead of conventional glycerol or thickener-based modifiers. This parameter change in the viscosity modifier type allows maintenance of ink droplet landing accuracy while preserving drying properties, as reduced isomaltulose has different evaporation and interaction characteristics compared to traditional modifiers.
Solution Approach 2:
The patent creates a composite ink formulation combining reduced isomaltulose as viscosity modifier with the optimized solvent system (monohydric alcohol, lower alcohol, water, wetting agents). This composite approach achieves both good printing characteristics and fast drying properties by leveraging the complementary properties of each component.
4Manufacturing precision
If thickeners (sodium alginate or hydroxypropyl methylcellulose) are used as viscosity modifiers, then ink droplet landing accuracy is improved, but discharge stability deteriorates due to reduced solubility in fast-drying solvents
Solution Approach 1:
The patent changes the chemical composition parameter of the viscosity modifier from conventional thickeners (sodium alginate, hydroxypropyl methylcellulose) to reduced isomaltulose. This parameter change ensures compatibility with fast-drying solvent systems, maintaining solubility and discharge stability while achieving the required ink droplet landing accuracy through appropriate viscosity control.
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 formulation effectively suppresses photodiscoloration and photofading, maintains lightfastness, and ensures excellent discharge stability and drying properties, thereby improving the visibility and longevity of printed images on tablets.
Implementation Method 1
Some food dyes contained in the inks and the like cause significant discoloration and/or fading due to light. The inkjet ink contains Red No. 102, reduced isomaltulose, and, as a solvent, water, monohydric alcohol, and a wetting agent... effectively suppresses photodiscoloration and photofading, maintains lightfastness
Implementation Method 2
the use of the thickener, such as sodium alginate or hydroxypropyl methylcellulose, as the viscosity modifier has reduced the solubility of the thickener in the fast-drying solvent... the compounding ratio of the reduced isomaltulose is in the range of 3.0 mass% or more and 8.5 mass% or less based on the total mass of the inkjet ink
Implementation Method 3
When a solvent contained in the inkjet inks and the like is a fast-drying solvent (solvent containing a lower alcohol and water)... the compounding ratio of the monohydric alcohol is in the range of 30 mass% or more and 60 mass% or less based on the total mass of the inkjet ink
Data Source
Figure 1A~2
Figure 3~5
AI summary
There is provided an inkjet ink having drying properties, lightfastness, and discharge stability and tablet printed matter including printed parts printed with the inkjet ink. An ink according to this embodiment contains: Red No. 102; reduced isomaltulose; and, as a solvent, water, monohydric alcohol, and a wetting agent, in which the monohydric alcohol includes at least one type among ethanol, NPA, and IPA, the wetting agent includes at least one type of glycerol and PG, the compounding ratio of the Red No. 102 is in the range of 0.5 mass% or more and 3.0 mass% or less based on the total mass of the inkjet ink, the compounding ratio of the monohydric alcohol is in the range of 30 mass% or more and 60 mass% or less based on the total mass of the inkjet ink, and the compounding ratio of the wetting agent is in the range of 0.05 mass% or more and 10 mass% or less based on the total mass of the inkjet ink.