Photocurable Ink Composition for LED Curing and PVC Adhesion
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Solution Overview
Problem
Photocurable ink compositions for inkjet printing on polyvinyl chloride sheets face challenges with adhesion, cockling, and compatibility with low-energy light sources like LEDs, while also requiring solvent and scratch resistance and storage stability.
Innovation Solution
A photocurable ink composition containing specific monomers such as monofunctional and multifunctional monomers with ether and cyclic structures, a trimethylol propane skeleton, and an acyl phosphine oxide photopolymerization initiator, optimized for use with LEDs, ensuring excellent adhesion, curability, and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a component that dissolves the base material is blended into the ink to improve adhesion, then adhesion to polyvinyl chloride sheets is improved, but the printed matter cockles easily
Solution Approach 1:
The patent changes the chemical composition parameters of the ink by specifying precise ratios of vinyl formamide (0.1-10 mass%), N-vinyl caprolactam (5-30 mass%), and other monomers. This parameter optimization allows the ink to achieve both good adhesion to PVC and reduced cockling, resolving the contradiction between adhesion improvement and printing quality maintenance
Solution Approach 2:
The patent creates a composite ink formulation combining multiple monomers with different functions: vinyl formamide for adhesion, N-vinyl caprolactam for flexibility and cockling prevention, and other photopolymerizable monomers for curing. This composite approach allows simultaneous achievement of adhesion, flatness, and curability
2Reliability
If conventional high-energy light sources like metal halide lamps are used for curing, then curability is achieved, but problems occur such as generation of ozone, increased equipment size, and shorter service life
Solution Approach 1:
The patent changes the curing parameters by selecting photopolymerizable monomers with absorption characteristics matching LED emission wavelengths. The ink formulation is optimized to be curable under LED irradiation, enabling transition from high-energy metal halide lamps to low-energy LEDs, thereby eliminating ozone generation while maintaining curability
Solution Approach 2:
The patent enables substitution of the lighting system by designing an ink composition that responds to LED light instead of requiring high-energy UV lamps. This replaces the mechanical/optical system of metal halide lamps with a more efficient LED system, reducing harmful effects while achieving the same curing function
3Strength
If photocurable materials that form tough films are used, then film strength is improved, but adhesion to base materials decreases because the films are very hard
Solution Approach 1:
The patent optimizes the composition parameters by incorporating flexible monomers like N-vinyl caprolactam (5-30 mass%) alongside toughening components. This parameter balance creates a film with both strength and flexibility, maintaining adhesion to PVC substrates while achieving the required mechanical durability for outdoor advertisements
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 composition achieves remarkable curability under UV light, strong adhesion to polyvinyl chloride sheets, solvent resistance, scratch resistance, and discharge stability, while maintaining low viscosity and safety features like a high flash point.
Implementation Method 1
a photopolymerization initiator by 3 to 20 percent by mass relative to the total mass of the photopolymerizable component; wherein, the viscosity of said photocurable ink composition for inkjet printing is 100 mPa·s or less at 25°C
Data Source
AI summary
An object of the present invention is to provide a photocurable ink composition for inkjet printing that exhibits good properties including curability in thin film form under ultraviolet light, especially the ultraviolet light generated by a light source using light-emitting diodes (LEDs), adhesion to polyvinyl chloride sheet, etc., solvent resistance, scratch resistance, discharge stability, and storage stability. A photocurable ink composition for inkjet printing that contains: a photopolymerizable compound that contains: virtually no vinyl formamide; 0.1 to 20 percent by mass of a monofunctional monomer containing an ether group relative to the total mass of the photopolymerizable component; 65 to 85 percent by mass of a monofunctional monomer containing a cyclic structure relative to the total mass of the photopolymerizable component; 0.1 to 25 percent by mass of a multifunctional monomer containing an amino group relative to the total mass of the photopolymerizable component; and 5 to 35 percent by mass of a monomer containing a trimethylol propane skeleton relative to the total mass of the photopolymerizable component; and an acyl phosphine oxide photopolymerization initiator by 3 to 20 percent by mass relative to the total mass of the photopolymerizable component; wherein the viscosity of said photocurable ink composition for inkjet printing is 100 mPa·s or less at 25°C.