Inkjet Ink Composition with Crosslinked Latex Polymers
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Solution Overview
Problem
Inkjet inks face challenges in maintaining polymer dispersion and achieving sufficient durability, particularly in water-based systems, where polymers fail to form robust films that withstand mechanical and chemical forces, leading to issues with rub resistance and solvent resistance.
Innovation Solution
The use of latex polymers prepared via emulsion polymerization with hydrophobic, acidic, and cross-linkable monomers, along with a cross-linker compound that reacts after the aqueous solvent's depletion, forming a strong, cross-linked film that enhances durability through inter-particle interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymers are used to improve durability of inkjet printed inks, then durability is improved, but the polymer dispersion becomes difficult to maintain due to water-like viscosity of inkjet inks
Solution Approach 1:
The patent changes the physical and chemical parameters of the polymer system by using pre-formed latex polymer particles with specific viscosity characteristics (0.1 to 10 Pascal seconds) and incorporating cross-linkable functional groups. This allows the polymer to maintain dispersion in water-based inkjet inks while still forming durable films after printing through cross-linking reactions.
Solution Approach 2:
The patent creates a composite system combining latex polymer particles with cross-linkable functional groups and cross-linking agents. This composite approach allows the polymer to remain dispersed in the aqueous ink medium during printing while forming a cross-linked network structure in the printed film that provides enhanced durability and rub resistance.
2Reliability
If polymers form films in inkjet inks, then durability is improved, but the films fail to withstand mechanical and chemical forces such as rubbing and solvent exposure
Solution Approach 1:
The patent incorporates cross-linkable functional groups within the polymer particles before printing. These pre-positioned reactive groups remain dormant during the printing and drying process, then activate to form cross-links after the ink has dried, creating a strengthened film structure that provides superior rub and solvent resistance.
Solution Approach 2:
The patent employs cross-linking reactions that create strong chemical bonds between polymer chains. This cross-linking network dramatically enhances the film's resistance to mechanical degradation from rubbing and chemical attack from solvents, transforming the film from a weak physical structure to a robust chemically-bonded network.
3Reliability
If chemical fixers or bonding agents are used to improve waterfastness, then highlighter fastness is improved, but rub resistance does not exhibit desired improvement
Solution Approach 1:
The patent pre-incorporates cross-linkable functional groups within the polymer particles themselves, rather than relying on separate chemical fixers applied after printing. This preliminary preparation ensures that cross-linking occurs uniformly throughout the film structure, providing both waterfastness and superior rub resistance simultaneously.
Solution Approach 2:
The patent creates a composite polymer structure where cross-linkable functional groups are integrated within the polymer matrix. This composite approach allows the film to achieve both waterfastness (through cross-linking) and rub resistance (through the strengthened network structure), overcoming the limitations of conventional chemical fixers that only provide waterfastness.
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 solution significantly improves the inkjet ink's durability by increasing rub resistance, highlighter smearfastness, wet smudgefastness, and solvent resistance, as demonstrated by reduced white spots and improved performance in aggressive testing conditions.
Implementation Method 1
latex polymers prepared via emulsion polymerization with hydrophobic, acidic, and cross-linkable monomers
Implementation Method 2
cross-linker compound that reacts after the aqueous solvent's depletion, forming a strong, cross-linked film
Data Source
AI summary
An inkjet ink composition includes latex polymer particles. The latex polymer particles are present in the ink composition in an amount ranging from about 0.5 wt % to about 40 wt %. The latex polymer particles have: a Tg ranging from about −40° C. to about 125° C.; and up to about 100% of total cross-linkable sites being present: on surfaces of the latex polymer particles; throughout a bulk of the latex polymer particles; or combinations thereof. The latex polymer particles are formed from monomers including at least one hydrophobic monomer, at least one acidic monomer, and at least one crosslinkable monomer, the at least one crosslinkable monomer including at least one keto group. The ink composition further includes at least one cross-linker compound selected from the group consisting of diamino compounds, polyamino compounds, and combinations thereof. Yet further, the ink composition includes at least one colorant and at least one aqueous solvent. The latex polymer particles are configured to form a crosslinked latex polymer film as and/or after the aqueous solvent is depleted from the latex polymer particles after the ink composition is applied by inkjet printing onto a medium.