Inkjet Adhesive Formulation for Cold Foil Printing Detail Preservation
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Solution Overview
Problem
The existing cold foil printing methods using flexographic inks are limited in versatility and productivity, as they cannot easily accommodate changes in design or language during a printing run, and the transition to inkjet inks results in excessive spreading and loss of detail due to differences in viscosity and film thickness.
Innovation Solution
An inkjet adhesive formulation comprising two or more monofunctional monomers with a log D octanol/water value of 1.1 or higher, along with photoinitiators, that balances through and surface curing properties to prevent excessive spreading and ensure proper adhesion, while being free from coloring agents and multifunctional monomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If inkjet inks are used as adhesive to vary design and increase productivity, then versatility and productivity are improved, but excessive spreading and loss of detail occur due to lower viscosity and thicker film
Solution Approach 1:
The patent applies parameter changes by carefully controlling the viscosity of the inkjet adhesive within a specific range (10-50 mPa·s at 25°C) and adjusting film thickness parameters to prevent excessive spreading while maintaining the benefits of inkjet printing versatility. This resolves the contradiction by optimizing physical parameters to achieve both design flexibility and image precision.
2Ease of operation
If inkjet inks with lower viscosity are used, then ease of jetting and deposition is improved, but excessive spreading occurs resulting in loss of image detail
Solution Approach 1:
The patent optimizes the viscosity parameter to a specific range (10-50 mPa·s) that balances jetting ease with spreading control. This parameter optimization allows the inkjet adhesive to be properly deposited while maintaining sufficient viscosity to prevent excessive spreading and preserve image detail.
3Reliability
If the adhesive film is made thicker to ensure complete coverage, then adhesion coverage is improved, but spreading increases and fine details are lost
Solution Approach 1:
The patent controls the film thickness parameter within an optimized range that provides sufficient coverage for reliable adhesion while preventing excessive spreading. By carefully managing this parameter, the system achieves complete coverage without sacrificing fine image details.
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 inkjet adhesive achieves high-lustre metallic images with preserved fine details and pinhole-free block areas, demonstrating good adhesion to substrates and flexibility, thereby enhancing the versatility and productivity of the cold foil printing process.
Implementation Method 1
one or more photoinitiators, wherein the inkjet adhesive... contains less than 0.5% by weight of monomers having a log D octanol/water of lower than 1.1
Implementation Method 2
subjecting the adhesive to a first curing by exposing the adhesive to UV light in a dosage range of 140-170mJ/cm2
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention provides an inkjet adhesive comprising: one or more monofunctional monomers, each having a log Doctanol/water of 1.1 or higher; and one or more photoinitiators, wherein the inkjet adhesive is free from monomers having a log Doctanol/water of lower than 1.1. The inkjet adhesive is particularly formulated for use in a method of cold foil printing. The inkjet adhesive contains only low polarity monomers to provide the inkjet adhesive with the ideal balance of through and surface curing properties required for cold foil printing. The monofunctional monomers also provide the inkjet adhesive with good adhesion properties.