Aqueous Coating Agent for Inkjet Scratch Resistance
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Solution Overview
Problem
Pigment ink-jet recorded materials face issues with scratch resistance, water resistance, and gloss due to the presence of pigment on the surface, and existing solutions either require high-cost laminators or compromise on ink ejectability when using silicone polymers as additives.
Innovation Solution
An aqueous coating agent containing a graft copolymer with a silicone-based side chain and an ethylenically unsaturated carboxylic acid-containing monomer is applied using the ink-jet system, providing scratch resistance, water resistance, and gloss while maintaining high ink ejectability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a protective layer is formed by film lamination or liquid lamination to improve scratch resistance and gloss, then scratch resistance and gloss are improved, but high-cost laminators are required
Solution Approach 1:
The invention extracts the protective layer formation process from the expensive film lamination or liquid lamination equipment, and integrates it into the existing ink-jet recording system by ejecting a coating solution that forms a protective topcoat layer, thereby eliminating the need for high-cost laminators
Solution Approach 2:
The invention merges the protective layer formation function with the ink-jet recording system by using the same ejection mechanism to apply both pigment ink and coating solution, combining two functions (recording and protection) into one integrated system
2Strength
If silicone polymer is added to pigment ink to improve scratch resistance, then scratch resistance is improved, but pigment dispersion deteriorates and ink ejectability worsens
Solution Approach 1:
The invention segments the silicone polymer into a graft copolymer structure where silicone-based side chains are grafted onto a main chain containing ethylenically unsaturated carboxylic acid-containing monomers, allowing the silicone to provide scratch resistance while the main chain maintains compatibility with pigment dispersion and ink ejectability
Solution Approach 2:
The invention changes the molecular structure parameters of the silicone polymer by controlling the acid value (40-200 mg-KOH/g) and weight-average molecular weight (5,000-30,000) of the graft copolymer, optimizing the balance between scratch resistance and ink ejectability
3Stability of the object's composition
If emulsion resin is used in coating solution to improve water resistance, then water resistance is improved, but ink ejectability deteriorates
Solution Approach 1:
The invention changes from using emulsion resin to using a graft copolymer with specific molecular weight (5,000-30,000) and acid value (40-200 mg-KOH/g) parameters, which provides adequate water resistance while maintaining low viscosity for good ink ejectability
Data Source
AI summary
The object of the invention is to provide an aqueous coating agent which I applied onto a recording medium in the ink-jet system to form a film excellent in scratch resistance, water resistance and gloss on the surface of an image, and an aqueous coating solution containing this aqueous coating agent. The means for solving is an aqueous coating agent for pigment ink-jet, which is characterized by comprising a graft copolymer that has a silicone-based side chain, and an ethylenically unsaturated carboxylic acid-containing monomer as an essential constituent in a main chain, and has an acid value in the range from 40 to 200 mg-KOH/g (solid) and a weight-average molecular weight in the range from 5,000 to 30,000; and an aqueous coating solution for pigment ink-jet comprising the aqueous coating agent which is characterized in that the aqueous coating solution is charged into a tank different from a tank for pigment ink, and is ejected and applied onto a recorded material from a nozzle different from a nozzle for pigment ink in ink-jet system.