Active Energy Ray-Curable Ink Adhesion Stretchability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional active energy ray-curable inks fail to achieve a balance between adhesion to substrates, hardness, and stretchability, which are essential for industrial applications such as printing on processed substrates.
Innovation Solution
The development of an active energy ray-curable ink containing specific polymerizable compounds, including monofunctional and bifunctional monomers with high glass transition temperatures, which form a cured product with enhanced adhesion, hardness, and stretchability by incorporating monomers like hydroxyethyl(meth)acrylamide, isobornyl (meth)acrylate, and neopentyl glycol di(meth)acrylate, capable of dissolving polycarbonate substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional active energy ray-curable ink is used, then adhesion to substrate is achieved, but the cured film becomes hard and brittle, losing stretchability
Solution Approach 1:
The patent changes the chemical parameters of the polymerizable compounds by specifying monomers with glass transition temperatures of 90°C or higher (such as isobornyl (meth)acrylate, adamantyl (meth)acrylate, and (meth)acryloylmorpholine) in specific proportions (50-95 mass% monofunctional, 5-50 mass% bifunctional). This parameter optimization resolves the contradiction by achieving both strong adhesion (70 or greater in cross-cut test) and stretchability (2 or greater in elongation test) simultaneously.
Solution Approach 2:
The patent creates a composite polymer system by combining multiple types of monomers with different functions: monofunctional monomers provide adhesion and hardness, while bifunctional monomers contribute to stretchability and flexibility. This composite approach allows the cured film to exhibit both strong substrate bonding and mechanical flexibility required for processed substrates.
2Strength
If monomers with high glass transition temperature are used to improve hardness, then adhesion is enhanced, but stretchability deteriorates
Solution Approach 1:
The patent optimizes the glass transition temperature parameter by selecting monomers whose homopolymers have Tg of 90°C or higher, but controls their proportion and combines them with bifunctional monomers. This parameter balancing achieves adhesion of 70 or greater while maintaining stretchability of 2 or greater, resolving the apparent contradiction between hardness and flexibility.
Solution Approach 2:
The patent applies local quality by having different monomer types contribute different properties to specific regions of the polymer network. The monofunctional monomers with high Tg provide localized adhesion and hardness at the substrate interface, while the bifunctional monomers provide localized flexibility within the film bulk, achieving overall balance.
3Strength
If the ink is designed for high adhesion to processed substrates, then substrate bonding improves, but processability (punching, stretching) deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters to include specific monomers capable of dissolving polycarbonate substrates (such as tetrahydrofurfuryl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate) in controlled amounts (5-50 mass% of bifunctional monomers). This achieves adhesion of 70 or greater while maintaining processability for punching and stretching operations.
Solution Approach 2:
The patent uses specific monomers as intermediaries that can dissolve the substrate material (polycarbonate) to create a strong chemical bond between the cured film and substrate. These intermediary monomers act as molecular bridges, providing both adhesion and flexibility for subsequent processing operations.
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 produces a cured product with stretchability of 2 or greater and adhesion of 70 or greater to polycarbonate substrates, offering improved punching processability and maintaining high adhesion and hardness, thus addressing the limitations of conventional inks.
Implementation Method 1
active energy ray-curable ink... applying active energy rays... to thereby cure the active energy ray-curable ink
Data Source
Figure 1~2
Figure 3
AI summary
An active energy ray-curable ink which contains: polymerizable compounds containing a monofunctional polymerizable monomer a homopolymer of which has Tg of 90°C or higher, wherein a cured product obtained by forming a coating film having an average thickness of 10 µm on a polycarbonate substrate using the ink, and 15 seconds later, and applying active energy rays having a light quantity of 1,500 mJ/cm2 to the coating film to cure satisfies the following (1) and (2): (1) a stretchability of the cured product represented by the following equation is 2 or greater, when the cured product is stretched by a tensile tester at a tensile speed of 20 mm/min, and temperature of 180°C, and Stretchability=length after tensile test/length before tensile test (2) adhesion between the substrate and the cured product as measured by a cross-cut test in accordance with JIS K5400 is 70 or greater.