Polyurethane Polymer Pigment Inkjet Ink Nozzle Clogging
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Solution Overview
Problem
Existing inkjet ink compositions face challenges in achieving stable dispersion of pigments in liquid vehicles, leading to nozzle clogging and poor print quality due to the need for external dispersants and the instability of high molecular weight polymers.
Innovation Solution
Aqueous inkjet compositions incorporating a self-dispersed pigment and a polyurethane polymer, where at least 5% of the polyurethane is associated with the pigment and 5% is unassociated, with the polyurethane being formed by polymerizing a pre-polymer in the presence of the pigment, providing improved dispersibility and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If external dispersants are added to improve pigment dispersibility, then pigment dispersibility is improved, but the complexity of the ink composition increases and stability may deteriorate
Solution Approach 1:
The pigment is modified with polymeric material during the pigment formation process, enabling it to self-disperse in the ink vehicle without requiring external dispersants. The pigment particles inherently possess dispersing capabilities through the attached polymeric material, which provides steric stabilization and prevents aggregation.
Solution Approach 2:
The invention combines the pigment formation process with polymer attachment in a single integrated process. The polymeric material is incorporated into the pigment structure during synthesis, merging the functions of pigment core formation and surface modification into one step, thereby simplifying the overall ink composition.
2Reliability
If high molecular weight polymers are used to improve inkjet ink performance, then print performance is improved, but nozzle clogging occurs due to poor solubility
Solution Approach 1:
The high molecular weight polymeric material is selectively attached only to the pigment particle surfaces, while the bulk ink vehicle remains free of high molecular weight polymers. This localized placement of polymer provides the benefits of improved print performance and smear resistance at the pigment-vehicle interface without introducing clogging risks into the bulk ink system.
Solution Approach 2:
The pigment particle acts as an intermediary carrier for the high molecular weight polymeric material. The polymer is delivered to the ink system bound to pigment particles, which protects the polymer from direct interaction with nozzle components while still providing performance benefits in the printed image.
3Stability of the object's composition
If polymeric material is attached to pigment to improve dispersibility, then pigment dispersibility is improved, but the manufacturing process complexity increases
Solution Approach 1:
The polymeric material is attached to the pigment particles during the pigment formation process itself, before the pigment is used in ink formulation. This preliminary attachment ensures that dispersibility is built into the pigment product, eliminating the need for separate surface modification steps and simplifying downstream manufacturing.
Solution Approach 2:
The pigment production process is segmented into distinct functional zones: a high-shear mixing zone for initial pigment formation and polymer attachment, followed by a controlled aggregation zone for final particle structure development. This segmentation allows optimization of each stage for its specific function, improving overall manufacturing efficiency.
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 results in inkjet inks with enhanced smear resistance, jettability, droplet size control, viscosity stability, and optical density, maintaining performance over time without the need for external dispersants and reducing nozzle clogging.
Implementation Method 1
polymerizing at least a portion of the polyurethane pre-polymer in the mixture to form a polyurethane polymer
Implementation Method 2
a self-dispersed pigment... The self-dispersed pigment may comprise an appended organic group that may be at least one geminal bisphosphonic acid group
Implementation Method 3
at least 5 percent by weight of the polyurethane polymer is associated with the self-dispersed pigment
Data Source
AI summary
A composition useful as an inkjet ink is described as well as methods of making the composition. The composition includes a pigment and a polymer and the polymer may include a polyurethane. The composition exhibits properties that make it useful in thermal and piezo inkjet applications.