Crosslinked Diblock Polymeric Dispersants for Inkjet Stability
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Solution Overview
Problem
Current polymeric dispersants for inkjet inks lack the necessary stability, optical density, and chroma required for emerging inkjet applications, particularly in inkjet printing, where the inks are sensitive to water and require improved durability and image quality.
Innovation Solution
Aqueous dispersions using crosslinked polymeric dispersants with a block copolymer structure, comprising an A block for steric stabilization and a B block for ionic stabilization, crosslinked with agents like epoxide, carbodiimide, or silane, which provide enhanced stability and image properties by forming a crosslinked polymer matrix around the pigment particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If non-ionic polymeric dispersants are used to stabilize pigment particles in aqueous ink vehicle, then entropic or steric stabilization is provided, but the printed image becomes water sensitive
Solution Approach 1:
The polymeric dispersant is divided into two distinct blocks: a non-ionic hydrophilic section (A block) that provides steric stabilization, and an ionic section (B block) that provides electrostatic stabilization. This segmentation allows each block to perform its specific function independently, resolving the contradiction between dispersion stability and water sensitivity
Solution Approach 2:
The invention uses a composite polymeric dispersant structure combining non-ionic and ionic components in a single molecule. The A block (non-ionic) and B block (ionic) work synergistically to provide both steric and electrostatic stabilization, creating a composite material that overcomes the limitations of using either component alone
2Object-affected harmful factors
If ionic polymeric dispersants are used to stabilize pigment particles through charged double layer mechanism, then water resistance is improved, but dispersion stability under varying pH and ionic conditions deteriorates
Solution Approach 1:
The dispersant is segmented into an A block (non-ionic hydrophilic section) and a B block (ionic section). The A block provides pH-insensitive steric stabilization while the B block provides electrostatic repulsion, allowing the system to maintain dispersion stability across varying pH and ionic conditions while retaining water resistance
Solution Approach 2:
The invention changes the physical-chemical parameters of the dispersant by incorporating both non-ionic and ionic sections with different charge densities and hydrophilicities. This parameter diversification allows the dispersant to maintain effectiveness across a broader range of environmental conditions
3Illumination intensity
If conventional polymeric dispersants are used in inkjet inks, then basic dispersion is achieved, but stability, optical density, and chroma required for emerging applications are insufficient
Solution Approach 1:
The invention employs a composite diblock copolymer dispersant structure where the A block (non-ionic) and B block (ionic) provide complementary stabilization mechanisms. This composite approach enhances ink reliability, optical density, and chroma while maintaining ease of manufacture
Solution Approach 2:
Different sections of the polymeric dispersant are assigned different local qualities: the A block provides steric stabilization and the B block provides electrostatic stabilization. This local differentiation optimizes the overall performance of the dispersant for high-quality inkjet applications
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 crosslinked polymeric dispersants achieve stable and high-quality inkjet inks with improved optical density and durability, ensuring the ink's stability during storage and repeated jetting cycles, while maintaining water resistance and image quality.
Implementation Method 1
the dispersant comprising a crosslinkable moiety; wherein the crosslinkable moiety is crosslinked with a crosslinking agent
Implementation Method 2
The hydrophilic section provides entropic or steric stabilization that stabilizes the solid particles in the aqueous ink vehicle
Implementation Method 3
The polymer provides stabilization through a charged double layer mechanism whereby ionic repulsion hinders the particles from flocculation
Data Source
AI summary
The present disclosure provides an aqueous dispersion comprising a solid particle and a polymeric dispersant, wherein the polymeric dispersant is a block copolymer comprising an A block and a B block, wherein the A block is a segment having a block size of about 5 to about 18 units, and comprises at least 50% by weight of a monomer having the following structure: CH2═CRC(O)O(CHR1CH2O)nR2; wherein R and R1 are H, or methyl; R2 is alkyl of 1-4 carbon atoms or phenyl; and n is about 1 about 20; and the B block is a segment comprising an ionic monomer and at least one hydrophobic monomer; and wherein the dispersant comprises a crosslinkable moiety; wherein the crosslinkable moiety is crosslinked with a crosslinking agent selected from the group consisting of epoxide, carbodiimide, oxazoline, isocyanate, and silane; and wherein the aqueous dispersion has a pH of at least about 8.0. These dispersions when used in aqueous ink jet inks provide images with the requisite optical density and chroma needed for emerging ink jet applications.