Pretreatment Liquid for Inkjet Substrates
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Solution Overview
Problem
Conventional aqueous inkjet inks face challenges with low absorption substrates such as coated paper, art paper, and film substrates, resulting in poor image quality due to inadequate penetration, drying issues, and adhesion problems, along with storage stability concerns when using pretreatment liquids with resins and coagulants.
Innovation Solution
A pretreatment liquid comprising a coagulant, surfactant, and resin, specifically a polyoxyalkylene alkylamine-based surfactant, is used to enhance wet-spreading, prevent bleeding, and improve adhesion on low absorption substrates, while maintaining storage stability over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional aqueous inkjet ink is used on a low absorption substrate, then the ink droplets cannot penetrate into the substrate, but this causes bleeding of the ink droplets and deterioration of image quality
Solution Approach 1:
A pretreatment liquid is applied to the low absorption substrate before inkjet printing to pre-establish penetration pathways. The pretreatment liquid contains penetration promoters that create channels in the substrate surface, enabling subsequent ink droplets to penetrate effectively and dry properly without bleeding.
Solution Approach 2:
The surface energy and porosity parameters of the substrate are temporarily modified by the pretreatment liquid. The pretreatment liquid reduces surface tension and increases effective porosity, allowing ink penetration. After drying, the substrate returns to its original state while maintaining improved ink reception properties.
2Reliability
If a pretreatment liquid forming an ink receiving layer is used, then the drying property is improved, but the coating film thickness must be increased which decreases drying property of the pretreatment liquid itself
Solution Approach 1:
The pretreatment liquid uses low molecular weight penetration promoters with high volatility and low surface tension. These components rapidly penetrate the substrate and evaporate quickly, providing effective ink reception without requiring thick coating films. The key parameter changes involve molecular weight, volatility, and surface tension of the pretreatment liquid components.
3Manufacturing precision
If a pretreatment liquid with resin and coagulant is used, then adhesion and image quality are improved, but storage stability deteriorates
Solution Approach 1:
The patent separates the coagulant from the pretreatment liquid formulation, using only penetration promoters, surfactants, and volatile solvents. This extraction of the coagulant component eliminates the precipitation and compatibility issues that cause storage instability, while still achieving good image quality through enhanced ink penetration and substrate preparation.
Solution Approach 2:
The pretreatment liquid uses volatile, low molecular weight components that evaporate completely after application. These short-living components provide their function during the printing process and then disappear, leaving no residual material that could cause storage stability issues in concentrated 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 solution provides excellent drying properties, adhesion, and image quality without mixed color bleeding or unevenness, along with long-term storage stability when combined with aqueous inkjet ink, effectively addressing the limitations of existing pretreatment liquids on low absorption substrates.
Implementation Method 1
a surfactant (B), specifically a polyoxyalkylene alkylamine-based surfactant, is used to enhance wet-spreading
Implementation Method 2
a coagulant (A) to prevent bleeding
Implementation Method 3
a resin (C) to improve adhesion on low absorption substrates
Implementation Method 4
enhance wet-spreading, prevent bleeding, and improve adhesion on low absorption substrates, while maintaining storage stability over time
Data Source
AI summary
A pretreatment liquid that can be used together with an aqueous inkjet ink comprising a pigment and water, whereinthe pretreatment liquid comprises a coagulant (A), a surfactant (B), a resin (C) and water,the coagulant (A) comprises a metal salt that includes at least a polyvalent metal salt,the surfactant (B) comprises a polyoxyalkylene alkylamine represented by the following general formula (1).