Radiation-Curable Ink Jet Composition Adhesion and Clogging
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Solution Overview
Problem
Radiation-curable ink jet compositions with high pigment content, particularly white inks, face challenges with adhesion, flexibility, and clogging due to high pigment content and specific gravity, leading to decreased discharge stability and increased clogging in conventional ink jet heads.
Innovation Solution
A radiation-curable ink jet composition comprising a polymerizable compound component with a high monofunctional monomer content, titanium oxide as a white color material, and a specific glass transition temperature range, combined with a cyclic liquid jet head for improved adhesion, flexibility, and scratch resistance, while maintaining discharge stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the pigment content is increased to achieve shielding property in white ink, then the shielding property is improved, but the adhesion of ink coating film decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the binder by specifying a monofunctional monomer content of 90 mass % or more and a weighted average glass transition temperature of 48°C or more. This parameter optimization allows the binder to maintain strong adhesion even when pigment content is increased to 15 mass % or more, resolving the contradiction between shielding property and adhesion
Solution Approach 2:
The patent creates a composite ink composition system combining high pigment content (15 mass % or more) with a specifically designed binder system (monofunctional monomer + photopolymerization initiator). This composite approach allows both high shielding property from pigment and strong adhesion from the optimized binder to coexist
2Illumination intensity
If the pigment content is increased to achieve shielding property, then the shielding property is improved, but the discharge stability deteriorates
Solution Approach 1:
The patent optimizes the binder composition parameters (monofunctional monomer content ≥90 mass %, weighted average Tg ≥48°C) to maintain composition stability and discharge performance even when pigment content is increased to 15 mass % or more, resolving the contradiction between shielding property and discharge stability
3Illumination intensity
If the specific gravity of white color material is increased, then the shielding property is improved, but clogging occurs more easily
Solution Approach 1:
The patent changes the binder's glass transition temperature parameter to 48°C or more, which maintains the binder's fluidity and compatibility with high specific gravity titanium oxide particles. This prevents particle aggregation and settling that would cause clogging, while still achieving high shielding property from the dense pigment
4Use of energy by moving object
If the monofunctional monomer content is increased to 90 mass % or more, then the adhesion and flexibility are improved, but the crosslinking density may decrease
Solution Approach 1:
The patent carefully balances the monofunctional monomer content (≥90 mass %) with the weighted average glass transition temperature (≥48°C) to achieve optimal adhesion and flexibility. The high Tg compensates for lower crosslinking density, maintaining overall coating strength while improving adhesion and flexibility
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 enhanced adhesion, flexibility, and scratch resistance while maintaining discharge stability, even with high titanium oxide content, and prevents clogging in ink jet heads by using a cyclic liquid jet head and optimizing the polymerizable compound ratios and glass transition temperatures.
Implementation Method 1
a photopolymerization initiator... irradiating the radiation-curable ink jet composition adhered to the recording medium with radioactive rays
Implementation Method 2
the composition is previously heated... a heating step of heating the radiation-curable ink jet composition in the liquid jet head to 40° C. or more
Data Source
AI summary
A radiation-curable ink jet composition includes a polymerizable compound component including a monofunctional monomer component and a multifunctional monomer component, a photopolymerization initiator, and titanium oxide as a white color material. The content of the monofunctional monomer component is 90 mass % or more based on the total amount of the polymerizable compound component, and the weighted average of the glass transition temperatures of homopolymers of the respective polymerizable compounds is 48° C. or more when the mass ratios of the contents of the respective polymerizable compounds are weighted.