Aqueous Ink Composition High-Boiling Alkanediol VOC Reduction
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Solution Overview
Problem
Conventional ink jet inks face challenges with storage stability, dischargeability, and VOC emission, particularly due to the use of 1,2-hexanediol, which has a low boiling point and contributes to environmental concerns.
Innovation Solution
An aqueous ink composition incorporating an alkanediol with a normal boiling point of 240° C. or higher and polyoxyethylene mono(2-ethylhexyl) ether, which enhances storage stability and reduces VOC emission while maintaining image granularity and discharge stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If 1,2-hexanediol is used as a solvent, then wettability and image granularity are improved, but VOC emission increases due to low boiling point
Solution Approach 1:
The patent changes the boiling point parameter of the diol solvent from low (1,2-hexanediol at 205°C) to high (240°C or higher) by selecting specific alkanediols such as 1,6-hexanediol, 1,5-pentanediol, or 2,4-pentanediol. This parameter change maintains the solvent's ability to improve image granularity while eliminating VOC emission concerns, as the high boiling point prevents evaporation under normal operating conditions.
Solution Approach 2:
The patent replaces the conventional short-lived volatile solvent (1,2-hexanediol) with a stable, non-volatile alternative (high-boiling-point alkanediol). This substitution eliminates the need for frequent solvent replacement due to evaporation and reduces environmental harm, while maintaining the functional benefits for image quality.
2Reliability
If conventional organic solvents are used, then discharge stability is maintained, but storage stability deteriorates over time
Solution Approach 1:
The patent employs a composite solvent system combining high-boiling-point alkanediol (providing storage stability) with controlled amounts of conventional solvents (maintaining discharge stability). This composite approach leverages the strengths of both material types: the alkanediol component prevents degradation during storage, while the conventional solvent component ensures proper discharge performance, achieving both stability requirements simultaneously.
3Object-generated harmful factors
If high-boiling-point alkanediol is used, then VOC emission is reduced, but wettability may deteriorate
Solution Approach 1:
The patent introduces polyoxyethylene mono(2-ethylhexyl) ether as an intermediary surfactant to bridge the wettability gap created by using high-boiling-point alkanediol. This intermediary substance has amphiphilic properties that enhance the wetting capability of the ink composition on the recording medium, compensating for the reduced surface activity of the high-boiling-point solvent while maintaining low VOC emission.
4Stability of the object's composition
If 1,2-hexanediol is used, then extraneous material is dissolved, but adhesion to nozzle face increases
Solution Approach 1:
The patent changes the chemical composition parameter of the solvent from 1,2-hexanediol to high-boiling-point alkanediols with specific molecular structures (1,6-hexanediol, 1,5-pentanediol, or 2,4-pentanediol). This structural parameter change maintains the solvent's ability to dissolve extraneous materials like salts through their hydroxyl groups, while the higher boiling point and different molecular structure reduce adhesion to the nozzle face, preventing clogging.
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 solution achieves improved storage stability, image granularity, and low VOC emission, aligning with environmental regulatory standards by using alkanediols with high boiling points and polyoxyethylene mono(2-ethylhexyl) ethers, effectively addressing the limitations of traditional ink compositions.
Implementation Method 1
1,2-hexanediol has a low boiling point and thus readily evaporates
Implementation Method 2
1,2-hexanediol has been widely used as a solvent for ink compositions. This is because, in addition to enhancing wettability of ink compositions
Implementation Method 3
1,2-hexanediol also serves to dissolve extraneous material, such as salts which may be generated in ink compositions, and thus can contribute to improvements in storage stability
Data Source
AI summary
An aqueous ink composition contains: an alkanediol having a normal boiling point of 240° C. or higher; polyoxyethylene mono(2-ethylhexyl) ether having a carbon number of 14 or more and 22 or less; and water, in which a content of the polyoxyethylene mono(2-ethylhexyl) ether having a carbon number of 14 or more and 22 or less is 0.4% by mass or lower based on the total amount of the aqueous ink composition.