Lithographic Ink Viscosity Control for Staining Resistance
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Solution Overview
Problem
Conventional lithographic inks, particularly active energy ray-curable inks, suffer from poor surface staining resistance and glossiness due to low cohesive force, leading to surface staining and irregular film leveling, which is exacerbated by high viscosity and instantaneous curing.
Innovation Solution
A lithographic ink with a specific viscosity range (5-100 Pa·s) and viscosity ratio (0.8-1.0) at different rotational speeds, incorporating a resin with a hydrophilic group and a polyfunctional (meth)acrylate with a hydroxyl group, enhancing cohesive force and fluidity while maintaining surface staining resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high molecular weight resin is applied to increase cohesive force, then surface staining resistance is improved, but viscosity increases causing lowered fluidity and poor ink transfer
Solution Approach 1:
The patent applies parameter changes by using a resin with a specific molecular weight range (5,000 to 100,000) and incorporating a polyfunctional (meth)acrylate with hydroxyl group in controlled amounts (30-70% by mass). This combination adjusts the viscosity parameters to achieve the optimal balance between cohesive force and fluidity, resolving the contradiction between surface staining resistance and ink transferability.
Solution Approach 2:
The patent creates a composite ink formulation by combining a resin having a hydrophilic group with a polyfunctional (meth)acrylate having a hydroxyl group. This composite material approach allows the ink to simultaneously achieve high cohesive force for surface staining resistance and appropriate fluidity for good ink transfer, as the two components work synergistically to balance these opposing requirements.
2Reliability
If resin concentration is increased to improve cohesive force, then surface staining resistance is improved, but viscosity increases causing lowered leveling property and irregular film surface
Solution Approach 1:
The patent controls the resin concentration by specifying a molecular weight range (5,000 to 100,000) and limiting the polyfunctional (meth)acrylate content to 30-70% by mass. This parameter optimization ensures the ink maintains sufficient cohesive force while preserving leveling properties, allowing the film to level properly before curing and achieving both surface staining resistance and smooth film surface.
3Productivity
If instantaneous curing is applied to improve productivity, then production speed is improved, but leveling time is reduced causing lowered gloss
Solution Approach 1:
The patent applies preliminary action by formulating the ink with specific resin and polyfunctional (meth)acrylate components that enable the film to level itself before curing occurs. The controlled viscosity and composition allow the ink to spread and level on the substrate prior to irradiation, ensuring smooth surface and gloss are achieved before the instantaneous curing process locks the film in place.
4Productivity
If low molecular weight resin is used in active energy ray-curable ink, then curability is improved, but cohesive force decreases causing poor repulsion property and surface staining
Solution Approach 1:
The patent creates a composite formulation combining a resin having a hydrophilic group with a polyfunctional (meth)acrylate having a hydroxyl group. This composite approach allows the use of lower molecular weight components for good curability while the synergistic interaction between the two materials provides sufficient cohesive force and repulsion properties to prevent surface staining, resolving the contradiction between curability and surface staining resistance.
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 achieves superior surface staining resistance and fluidity, resulting in high gloss and improved print quality with reduced misting and surface staining, even under high shear conditions.
Implementation Method 1
the cohesive force of the ink is insufficient under high shear during printing
Implementation Method 2
a resin having a hydrophilic group and the weight average molecular weight of the resin having a hydrophilic group is from 5,000 to 100,000, and a polyfunctional (meth)acrylate having a hydroxyl group
Implementation Method 3
a viscosity (A) at a rotational speed of 0.5 rpm, a viscosity (B) at a rotational speed of 20 rpm, and a viscosity (C) at a rotational speed of 50 rpm of 5 Pa·s or more and 100 Pa·s or less, the viscosities (A), (B), and (C) being measured by using a cone-plate rotating viscometer at 25°C
Implementation Method 4
an active energy ray-curable lithographic ink actively used because of high productivity provided by instantaneous curing
Data Source
AI summary
Provided is a lithographic ink having superior surface staining resistance and fluidity. Also provided is a method for manufacturing a printed material using the lithographic ink. The lithographic ink has all of a viscosity (A) at a rotational speed of 0.5 rpm, a viscosity (B) at a rotational speed of 20 rpm, and a viscosity (C) at a rotational speed of 50 rpm of 5 Pa·s or more and 100 Pa·s or less, the viscosities (A), (B), and (C) being measured by using a cone-plate rotating viscometer at 25°C, and has a viscosity ratio (C)/(B) of 0.8 or more and 1.0 or less.