Water-based Ink Titanium Oxide Redispersibility
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Solution Overview
Problem
Ink-jet printing methods face challenges with the precipitation and aggregation of titanium oxide in water-based inks, leading to reduced redispersibility and potential nozzle clogging, especially when printing is interrupted, due to the limitations of existing pigment dispersants designed for higher viscosity coatings.
Innovation Solution
A water-based ink formulation containing titanium oxide and a specific pigment dispersant with a constitutional unit derived from an anionic group-containing monomer and polyalkylene glycol (meth)acrylate, optimized with an acid value and molar addition of alkyleneoxide to enhance dispersibility and prevent aggregation, along with an ink-jet printing method that includes a dispersing mechanism to redisperse the ink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional pigment dispersants designed for higher viscosity coatings are used in water-based ink-jet inks, then dispersibility of titanium oxide is improved, but precipitation and aggregation occur during storage and after printing interruptions
Solution Approach 1:
The patent changes the chemical parameters of the dispersant by specifying it must be a polyacrylamide derivative with particular structural characteristics (amino groups from acrylamide or methacrylamide units). This parameter change transforms the dispersant's properties to be suitable for low-viscosity water-based ink-jet inks, preventing titanium oxide precipitation during storage and after printing interruptions while maintaining excellent dispersibility.
Solution Approach 2:
The patent creates a composite system by combining titanium oxide pigment with a specifically designed polyacrylamide derivative dispersant in water-based ink-jet ink. This composite formulation achieves synergistic effects where the dispersant's amino groups provide both dispersion and stabilization functions, resolving the contradiction between initial dispersibility and long-term stability against precipitation.
2Illumination intensity
If titanium oxide is used as a pigment in white ink for non-white ground printing media, then hiding power and image visibility are improved, but nozzle clogging occurs due to aggregation
Solution Approach 1:
The patent introduces a polyacrylamide derivative as an intermediary substance between titanium oxide pigment particles and the water-based ink-jet ink medium. This dispersant acts as a mediator that prevents direct aggregation of titanium oxide particles, maintaining their individual dispersion and preventing nozzle clogging while preserving the high hiding power and image visibility that titanium oxide provides on non-white ground media.
Solution Approach 2:
The patent replaces mechanical agitation or circulation systems that would be needed to prevent titanium oxide aggregation with a chemical solution approach. The polyacrylamide derivative dispersant provides steric and electrostatic stabilization through its molecular structure, substituting for mechanical prevention methods and eliminating nozzle clogging while maintaining image visibility.
3Productivity
If the ink is allowed to stand in the ink tank for a long period of time, then printing productivity is maintained, but titanium oxide precipitates and aggregates
Solution Approach 1:
The patent enables the ink system to self-stabilize titanium oxide dispersion during extended storage periods without requiring external intervention such as circulation or agitation. The polyacrylamide derivative dispersant provides continuous steric and electrostatic protection to titanium oxide particles, allowing the ink to maintain uniform composition and preventing precipitation even when the printing apparatus is idle for long periods, thus supporting continuous productivity.
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 formulation achieves excellent redispersibility of titanium oxide, preventing nozzle clogging and ensuring consistent printing quality even after interruptions, by using a pigment dispersant that effectively stabilizes the titanium oxide through electrostatic and steric repulsion forces.
Implementation Method 1
The formulation achieves excellent redispersibility of titanium oxide, preventing nozzle clogging and ensuring consistent printing quality even after interruptions, by using a pigment dispersant that effectively stabilizes the titanium oxide through electrostatic and steric repulsion forces.
Implementation Method 2
The formulation achieves excellent redispersibility of titanium oxide, preventing nozzle clogging and ensuring consistent printing quality even after interruptions, by using a pigment dispersant that effectively stabilizes the titanium oxide through electrostatic and steric repulsion forces.
Implementation Method 3
An ink-jet printing method that includes a dispersing mechanism to redisperse the ink.
Data Source
Figure 1
AI summary
The present invention relates to [1] a water-based ink for ink-jet printing containing titanium oxide (A) and a pigment dispersant (B), in which the pigment dispersant (B) contains a constitutional unit derived from an anionic group-containing monomer (a) and a constitutional unit derived from a polyalkylene glycol (meth)acrylate (b); an average molar number of addition of an alkyleneoxide in the polyalkylene glycol (meth)acrylate (b) is from 15 to 100; an acid value of the pigment dispersant (B) is from 100 to 400 mgKOH/g; and a content of the pigment dispersant (B) in the water-based ink is from 0.3 to 18 parts by mass on the basis of 100 parts by mass of the titanium oxide (A), and [2] an ink-jet printing method of ejecting the water-based ink described in the above item [1] onto a printing medium using an ink-jet printing apparatus to print characters or images on the printing medium. According to the present invention, there are provided a water-based ink for ink-jet printing which contains titanium oxide as a pigment, and is excellent in redispersibility, and an ink-jet printing method.