Polyester Dispersants for Ceramic Ink Jet Stability
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Solution Overview
Problem
Existing technologies face challenges in dispersing inorganic metal oxide pigments for ceramic and glass coloration, particularly in achieving consistent and intense coloration through digital printing, as they tend to settle and clog ink jet nozzles due to large particle sizes and lack of colloidal stability.
Innovation Solution
A composition comprising a mixed metal oxide particulate solid, a mid-polar fatty acid ester medium, and a dispersing agent with a specific formula (RC(=O) -[A] m -[B] n - Z) that forms a random or blocky copolymer, stabilizing the particles and allowing for colloidally stable non-aqueous ink jet inks for ceramic and glass coloration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If inorganic metal oxide pigments are used for ceramic and glass coloration, then intense coloration is achieved, but the pigments settle and clog ink jet nozzles due to large particle sizes and lack of colloidal stability
Solution Approach 1:
The patent applies parameter changes by reducing the particle size of inorganic metal oxide pigments from conventional large sizes to sub-700nm range, and by modifying the chemical composition of the vehicle to include specific surfactants and solvents that enhance colloidal stability. These parameter changes resolve the contradiction by enabling intense coloration through fine particles while preventing settling and nozzle clogging through stabilized dispersion.
Solution Approach 2:
The patent introduces surfactants and stabilizing agents as intermediaries between the inorganic metal oxide pigments and the vehicle. These intermediaries adsorb onto particle surfaces, providing steric or electrostatic stabilization that prevents aggregation and settling, thereby maintaining colloidal stability while preserving the intense coloration properties of the pigments.
2Reliability
If particle size of inorganic pigments is reduced for better ink jet performance, then colloidal stability improves, but milling time increases and manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-dispersing the inorganic metal oxide pigments in the vehicle containing surfactants and stabilizing agents before the actual milling process. This preliminary dispersion prevents agglomeration and facilitates more efficient size reduction during milling, achieving the required sub-700nm particle size with reduced milling time compared to conventional approaches.
Solution Approach 2:
The patent creates a composite system comprising inorganic metal oxide pigments, surfactants, stabilizing agents, and vehicle in a carefully balanced formulation. This composite approach allows the different components to work synergistically, where the surfactants and stabilizers protect particles during milling and prevent re-aggregation, thereby achieving fine particle sizes without excessive milling time.
3Ease of manufacture
If conventional dispersants are used for inorganic pigments, then dispersion is achieved, but settling and nozzle plugging occur due to insufficient colloidal stability
Solution Approach 1:
The patent replaces conventional single-function dispersants with a composite system containing multiple specialized additives: surfactants for initial wetting and dispersion, and specific stabilizing agents for long-term colloidal stability. This composite additive package provides both ease of manufacture through good dispersion and reliability through prevention of settling and nozzle plugging.
Solution Approach 2:
The patent changes the chemical parameters of the dispersant system by selecting specific surfactant types and stabilizing agents with appropriate HLB values, molecular weights, and functional groups. These parameter changes optimize the balance between dispersion capability and colloidal stability, resolving the contradiction between ease of manufacture and reliability.
4Extent of automation
If inorganic metal oxide pigments are jetted through ink jet nozzles, then digital printing is achieved, but nozzle plugging occurs due to particle size and aggregation
Solution Approach 1:
The patent changes the particle size parameter to sub-700nm range and modifies the vehicle composition to include flow-enhancing surfactants and stabilizers. These parameter changes ensure that particles remain individually dispersed and do not aggregate, enabling smooth flow through ink jet nozzles while maintaining digital printing capability.
Solution Approach 2:
The patent introduces surfactants and stabilizing agents as intermediaries that adsorb onto particle surfaces, providing steric or electrostatic stabilization. These intermediaries prevent particle aggregation and reduce inter-particle friction, thereby improving nozzle flowability while preserving the digital printing functionality.
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 provides stable ink jet ink dispersions with particle sizes below 700nm, reducing milling time, improving filterability, and achieving brighter, more homogeneous color shades with reduced metal contaminants, enhancing the efficiency of digital printing on ceramic and glass substrates.
Implementation Method 1
to colloidally stabilize the particles of inorganic metal oxides in ink jet inks to avoid settling of the denser mixed metal oxide pigments
Implementation Method 2
The particle size of the inorganic metal oxide pigments generally has not been studied and controlled to the extent that particle sizes of pigments has been controlled for use in polymeric organic coatings and inks
Data Source
AI summary
The invention provides dispersed inorganic mixed metal oxide pigment compositions in a non-aqueous media utilizing a polyester dispersant having a terminal hydroxyl, tertiary amine or quaternized amine anchoring group and a mixed metal oxide pigment. The metal oxide pigment is of the type used to colour ceramic or glass articles. A milling process using beads is also described to reduce the mixed metal oxide particle size to the desired range. A method of using the mixed metal oxide dispersion to digitally print an image on a ceramic or glass article using the dispersion jetted through a nozzle and firing the coloured article is also described.