Single Pass White Ink Printing on Corrugated Board
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Solution Overview
Problem
Current single-pass printing methods on corrugated boards fail to maintain opacity and adhesion of white ink due to absorption into the substrate, leading to high costs and odor issues with traditional white substrates, and the need for a flexible, fast-curing, low-odor ink solution.
Innovation Solution
Applying a primer composition to seal the substrate followed by a white ink layer, which is then cured with actinic radiation, using a water-based or UV-curable primer and ink compositions with specific monomers and additives to ensure adhesion and minimal odor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If white ink is printed directly on porous corrugated board in single pass, then the printing process is efficient, but the white ink absorbs into the substrate and loses opacity
Solution Approach 1:
A primer layer is applied to the porous corrugated board substrate before printing the white ink. This preliminary action seals the porous surface, preventing the white ink from absorbing into the substrate and losing its opacity, while still allowing single-pass printing to proceed efficiently
2Speed
If UV-curable ink is used for fast curing, then the curing speed is fast, but the ink becomes brittle and cracks during creasing
Solution Approach 1:
The ink composition combines UV-curable components for fast curing with flexible polymer components that maintain flexibility after curing. This composite material approach allows the ink to cure rapidly while remaining flexible enough to withstand creasing without cracking
Solution Approach 2:
The ink formulation uses specific monomer and oligomer combinations with controlled molecular weights and functional groups to balance crosslinking density. This parameter optimization enables fast UV curing while maintaining adequate flexibility for post-printing operations like creasing
3Quantity of substance
If traditional monomers are used in inkjet ink, then the ink has low viscosity for jetting, but the monomers have high vapor pressure and distinct odors that can taint packaging
Solution Approach 1:
The patent uses monomers with specifically controlled molecular weights and functional groups that balance vapor pressure and viscosity. This parameter optimization reduces odor and tainting while maintaining jettable viscosity, and the UV curing process further reduces harmful emissions compared to traditional drying methods
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
Enables successful single-pass printing of white on non-white substrates with maintained opacity and reduced odor, allowing for subsequent color printing with CMYK or extended gamut inks, while providing flexibility and cost-effectiveness.
Implementation Method 1
applying a primer composition to seal selected surfaces of the non-white substrate
Implementation Method 2
white is imparted by a process of scattering light back to the viewer with minimal absorption
Implementation Method 3
The UV-curable white ink composition comprises... one or more photoinitiators
Data Source
AI summary
The present invention is directed to a method for single pass printing on an absorbent non-white substrate. The method comprises: (a) applying a primer composition to one or more selected surfaces of an absorbent non-white substrate to form a primer layer to seal the selected surfaces of the substrate, (b) drying the primer layer, (c) printing a white ink on the primer layer, and (d) drying or curing the white ink. The present invention also relates to low odor radiation curable white ink compositions. The composition comprises 10-40% w/w of 4-hydrobutylacrylate, 0.5-10% of a urethane (meth)acrylate oligomer, 10-55% of diacrylates, one or more photoinitiators, one or more additives, and one or more white pigments. The composition excludes many monofunctional monomers that have distinct odor and are commonly used in an ink jet composition.