Active Energy Ray Curable Ink Stretchability Hardness Trade-off
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Solution Overview
Problem
Conventional active energy ray curable inkjet inks have high hardness, resulting in poor stretchability and inability to follow substrate deformation during stretching processing.
Innovation Solution
A three-layer cured product is achieved by forming and irradiating active energy ray curable composition films on a polycarbonate substrate with specific thickness and light quantities, combining monofunctional reactive compounds with high and low glass transition temperatures to enhance stretchability and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional active energy ray curable inkjet ink is used to form a cured film, then the cured film has high hardness, but the stretchability is poor and the cured film cannot follow deformation of the substrate
Solution Approach 1:
The patent changes the chemical composition parameters of the curable composition by incorporating specific polymerizable compounds with controlled functional group numbers (1-5) and specific glass transition temperatures. This allows the cured film to achieve both adequate hardness and improved stretchability by adjusting the molecular structure and crosslinking density of the polymer network.
Solution Approach 2:
The patent creates a composite curable composition system that combines multiple polymerizable compounds with different properties (different functional group numbers, different glass transition temperatures, different molecular weights). This composite approach allows the cured film to exhibit both hardness and stretchability by integrating the complementary characteristics of different polymer components.
2Strength
If the cured film has high hardness, then strength is improved, but the cured film cannot be processed in a desired manner during stretching processing
Solution Approach 1:
The patent adjusts the glass transition temperature parameter of the polymerizable compounds within a specific range (50°C to 150°C) to optimize the balance between strength and processability. This temperature parameter control allows the cured film to maintain strength while becoming sufficiently flexible at processing temperatures to follow substrate deformation.
3Adaptability or versatility
If the stretchability of the cured film is improved, then the cured film can follow substrate deformation, but the hardness may be reduced
Solution Approach 1:
The patent uses a composite system of polymerizable compounds with different functional group numbers (combining low functionality compounds for flexibility with higher functionality compounds for crosslinking density). This composite structure allows the cured film to achieve both stretchability and hardness simultaneously by balancing the flexible polymer chains with the crosslinked network structure.
Solution Approach 2:
The patent creates local variations in crosslinking density and polymer chain flexibility within the cured film structure. Regions with different functional group densities provide localized hardness while other regions provide flexibility, allowing the overall film to exhibit both properties through spatial distribution of material characteristics.
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 resulting cured product exhibits stretchability of 1.1 or more and a glass transition temperature of 50° C. or more, maintaining strength while allowing for substrate deformation.
Implementation Method 1
irradiating the first film with an active energy ray having a light quantity of 1,500 mJ/cm2; forming a second film of the active energy ray curable composition
Data Source
AI summary
An active energy ray curable composition including a polymerizable compound is provided. When a three-layer cured product of the active energy ray composition is obtained by a specific procedure, the three-layer cured product has (1) a stretchability of 1.1 or more and (2) a glass transition temperature of 50° C. or more. The stretchability is defined by a ratio L2/L1, wherein L1 represents a first length of the cured product before a tensile test and L2 represents a second length of the cured product after the tensile test. The tensile test includes stretching the cured product along with the substrate with a tensile tester at a stretching speed of 20 mm/min and a temperature of 180° C.