Aqueous Inkjet Ink Polymer for Optical Density
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Solution Overview
Problem
Aqueous-based inkjet ink compositions using water-soluble dyes exhibit lower optical print density compared to other printing methods due to ink penetration into paper substrates, and they suffer from issues like poor water fastness and smear resistance.
Innovation Solution
An aqueous particle-free inkjet ink composition comprising a water-soluble dye colorant, a water-soluble polymer with specific recurring units, acid number, and molecular weight, and an aqueous medium, which eliminates the need for humectants and enhances print optical density without drying out in inkjet nozzles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aqueous-based inkjet ink compositions using water-soluble dyes are used, then the printing process is simple and cost-effective, but the optical print density is lower compared to other printing methods
Solution Approach 1:
The patent changes the chemical parameters of the ink composition by introducing a specific polymer electrolyte with controlled molecular weight (5,000-20,000) and acid number (100-200), which modifies the ink's interaction with the paper substrate to improve optical print density while maintaining the simplicity of the aqueous-based printing process
Solution Approach 2:
The patent creates a composite ink formulation by combining water-soluble dyes with a specific polymer electrolyte (such as polyacrylic acid or poly styrene-co-acrylic acid), forming a composite material that achieves both high optical print density and ease of manufacture through synergistic interactions between components
2Device complexity
If conventional aqueous inkjet inks are used, then the formulation is simple, but the ink dries out in inkjet nozzles during printing
Solution Approach 1:
The patent modifies the formulation parameters by selecting a polymer electrolyte with specific molecular weight and acid number characteristics that provide optimal balance between nozzle flow properties and drying prevention, achieving reliable printing without complex additives
Solution Approach 2:
The polymer electrolyte acts as an intermediary substance that mediates between the water-soluble dye and the paper substrate, preventing premature drying in the nozzles while controlling ink penetration into the paper to achieve high optical density
3Ease of operation
If aqueous dye-based inks are used, then the ink is easy to handle and store, but the images exhibit poor water fastness and smear resistance
Solution Approach 1:
The patent formulates a composite ink system where the polymer electrolyte creates a matrix that binds the water-soluble dye, providing both ease of handling and improved water fastness through the synergistic interaction between the polymer chains and dye molecules
Solution Approach 2:
The patent optimizes the acid number parameter of the polymer electrolyte (100-200) to achieve the right balance between ink solubility for easy handling and cross-linking density for improved water fastness and smear resistance
Data Source
AI summary
A method is useful for providing an ink jetted image with improved print optical density. The method includes use of an aqueous particle-free inkjet ink composition that consists essentially of: aqueous particle-free inkjet ink composition has a pH of 7 to 9, and consists essentially of: (A) a water-soluble dye colorant at 2-10 weight %, (B) a water-soluble polymer at 1-4 weight %, and an aqueous medium consisting essentially of water. The water-soluble polymer has an acid number or at least 130 and a molecular weight of 5,000-20,000. It comprises: (a) 55-80 mol % of recurring units derived from one or more ethylenically unsaturated polymerizable monomers selected from the group consisting of substituted or unsubstituted styrenes, (meth)acrylates, and combinations thereof, each (meth)acrylate comprising either a pendant phenyl group or an alkyl ester group having 12-20 carbon atoms; and (b) 20-35 mol % of recurring units comprising (meth)acrylic acid.