Ink Composition with Controlled Tg and Acid Value
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Solution Overview
Problem
Conventional ink jet recording-use ink compositions face issues with discharge stability, water resistance, and solvent resistance, particularly when printed on low or non-absorbing substrates, leading to problems like nozzle clogging and poor durability of printed matter.
Innovation Solution
An ink jet recording-use ink composition is developed, incorporating a binder resin with a glass transition temperature between 40°C and 90°C, a specific acid value calculation, and a nonionic surfactant, along with a reduced high-boiling solvent content, to enhance dispersion stability and prevent nozzle clogging, while maintaining excellent water and solvent resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a water-soluble resin or semi-dissolved colloidal dispersion is used as a binder resin, then the ink composition can be easily formulated and applied, but the ink composition adheres to the nozzle opening, lowers liquid repellency, and causes discharge instability and poor water/solvent resistance
Solution Approach 1:
The patent changes the chemical parameters of the binder resin by specifying a glass transition temperature range of 40-90°C and an acid value range of 15-50 mg KOH/g. These parameter changes transform the binder resin from conventional water-soluble resins that cause adhesion issues to a resin that maintains discharge stability while preventing nozzle clogging.
2Ease of manufacture
If a resin emulsion with high acid value (50 mg KOH/g or more) is used as a binder resin, then the ink composition can be formulated, but the printed matter has poor water resistance and solvent resistance, leading to insufficient durability
Solution Approach 1:
The patent precisely controls the acid value parameter of the binder resin to be in the range of 15-50 mg KOH/g, which is lower than conventional high acid value resins (≥50 mg KOH/g). This parameter change improves water and solvent resistance while maintaining formulability and discharge stability.
3Reliability
If a large amount of low-volatile solvent with high boiling point is used to maintain discharge stability, then discharge stability is improved, but drying property is significantly lowered and energy consumption increases
Solution Approach 1:
The patent changes the solvent composition parameters by limiting high boiling point solvents and instead using solvents with moderate boiling points in combination with a binder resin having Tg of 40-90°C. This parameter change maintains discharge stability while significantly improving drying properties and reducing energy consumption.
4Ease of operation
If glycerin is used as a wetting agent in aqueous ink compositions, then the ink composition can be applied smoothly, but drying property becomes poor particularly on low absorbing substrates
Solution Approach 1:
The patent extracts glycerin from the ink composition formulation. By removing this high-boiling wetting agent and replacing its function with a binder resin having controlled Tg (40-90°C) and acid value (15-50 mg KOH/g), the formulation achieves both smooth application and improved drying properties.
5Use of energy by moving object
If the amount of glycerin is reduced or removed to improve drying property, then drying property is improved, but the nozzle becomes clogged or ink composition solidifies in the flow path
Solution Approach 1:
The patent introduces a binder resin with specific Tg (40-90°C) and acid value (15-50 mg KOH/g) as an intermediary substance that replaces glycerin's wetting and flow-maintaining functions. This intermediary prevents nozzle clogging and ink solidification while allowing reduced glycerin content for improved drying.
6Reliability
If conventional binder resins are used to achieve good discharge stability, then discharge stability is improved, but water resistance and solvent resistance are poor, resulting in insufficient printed matter durability
Solution Approach 1:
The patent creates a composite formulation by combining a binder resin with specific Tg (40-90°C) and acid value (15-50 mg KOH/g) with carefully selected solvents and pigments. This composite material achieves simultaneous improvement in discharge stability, water resistance, and solvent resistance that cannot be achieved with conventional single-resin formulations.
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 composition achieves stable ink jet recording with reduced discharge defects, improved water and solvent resistance, and enhanced durability of printed matter on low or non-absorbing substrates, ensuring effective printing without nozzle clogging.
Implementation Method 1
incorporating a binder resin with a glass transition temperature between 40°C and 90°C
Implementation Method 2
a nonionic surfactant, along with a reduced high-boiling solvent content
Implementation Method 3
an ink composition that has excellent dispersion stability, is capable of creating a printed matter having excellent water resistance and solvent resistance
Data Source
AI summary
Provided is an aqueous ink jet-use ink composition which exhibits quick drying properties on a recording medium with low water-absorbing properties, exhibits good printed matter durability, is subject to few discharge defects such as printing head nozzle clogging or curved discharge, and exhibits excellent discharge properties. The present invention includes a binder resin, a surfactant, a pigment, a solvent and, if necessary, a pigment-dispersing resin. The binder resin has a glass transition temperature of 40-90°C and is dispersed as resin emulsion particles. The value of A, which is defined as the sum of the product of the acid value and the content in terms of parts by mass of the binder resin and pigment-dispersing resin, is 0-200 mg KOH/g. The surfactant is a non-ionic compound represented by formula (1), and the content of solvents having boiling points of 250°C or higher contained in the solvent is less than 5 parts by mass relative to 100 parts by mass of the ink composition. R1O-(R2O)n-H (1) (R1 is a straight-chain or branched chain alkyl group having 12-22 carbon atoms. R2 is an ethylene group or propylene group. n is an integer between 10 and 50.)