Polyurethane Binder Dispersion for Inkjet Printhead Clogging
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Solution Overview
Problem
Inkjet inks containing polymers often suffer from poor Sustained Printing and Recovery (SPAR) performance due to the formation of hard films on printhead nozzle plates, leading to clogging and reduced print quality, with existing mitigation strategies either reducing print speed or impacting image durability.
Innovation Solution
A polyurethane-based binder dispersion comprising isophorone diisocyanate, polyether polyol, and sulfonate or sulfonic acid functional groups is used in the inkjet ink, which forms softer films that reduce puddling and are easier to remove, maintaining high print quality and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer-containing inkjet inks are used to ensure image durability, then image durability is improved, but printhead clogging occurs due to hard film formation
Solution Approach 1:
The patent changes the chemical composition parameters of the polyurethane binder by incorporating specific polyols (polyether polyol with 1000-5000 g/mol molecular weight, polyester polyol with 500-3000 g/mol molecular weight) and controlling the NCO group content (2-10 mmol/g). This parameter optimization enables the polyurethane to form softer, more flexible films that resist clogging while maintaining image durability.
Solution Approach 2:
The patent creates a composite polyurethane binder system combining multiple components: polyisocyanate, polyether polyol, polyester polyol, and optionally polyamide polyol or carboxylic acid. This composite formulation synergistically combines the advantages of each component to achieve both durability and reduced clogging tendencies.
2Reliability
If printhead servicing is performed to prevent clogging, then printhead performance is maintained, but print speed decreases due to interruptions
Solution Approach 1:
The optimized polyurethane binder formulation provides self-protecting properties by forming films with appropriate flexibility and adhesion that naturally resist clogging and reduce the frequency of required servicing interventions, allowing continuous operation.
3Object-generated harmful factors
If polymer content in inkjet ink is reduced to prevent clogging, then printhead performance improves, but image durability deteriorates
Solution Approach 1:
The patent optimizes the polyurethane binder parameters including NCO group content (2-10 mmol/g), polyol molecular weights, and component ratios to achieve the minimum effective polymer concentration that provides both durability and reduced clogging. This precise parameter control allows maintaining adequate film-forming capability while minimizing harmful effects.
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 polyurethane-based binder dispersion enables continuous printing with minimal printhead servicing, increasing print speed and productivity while ensuring image durability and quality, even under stress conditions like hot corrugation.
Implementation Method 1
these polymers form films that are too 'hard' to re-dissolve or blast away
Implementation Method 2
when the polymer in the ink becomes concentrated enough (due to evaporation), it film-forms on the nozzle plate
Implementation Method 3
Forming 'softer' films can not only reduce puddling but can also make it easier to remove any build-up
Implementation Method 4
SPAR is defined as the reliability of an ink that is jetted continuously from the printhead for hours with no pauses or servicing
Data Source
Figure 1
AI summary
An inkjet ink composition comprising a polyurethane-based binder dispersion is described. The polyurethane-based binder dispersion comprises: a polyurethane, which comprises: (A) a polyisocyanate; (B) a first polyol having a chain with two hydroxyl functional groups at one end of the chain and no hydroxyl groups at an opposed end of the chain; (C) a second polyol having a chain with two hydroxyl functional groups at both ends of the chain; (D) a carboxylic acid functional group with two hydroxyl functional groups; and (E) a compound shown in formula (1): m(M+) n(X)-R-Y - (1), wherein m is 0 or 1, M is a metal, n is 2 to 10, X is an amino group, R is a C1 to C18 alkyl group, a C6 to C30 aromatic compound or a C4 to C20 aliphatic cyclic compound, and Y is SO3- or SO3H, with the proviso that when m is 0, Y is SO3H and when m is 1, Y is SO3-.