Polyurethane Inkjet Ink Drying Rate and Jetting Reliability
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Solution Overview
Problem
Inkjet inks face challenges in achieving faster drying and image durability on low and non-absorption substrates while maintaining reliable jetting performance, especially due to issues with volatility, nozzle clogging, and redispersibility.
Innovation Solution
The development of an aqueous inkjet ink composition that combines specific polyurethane binders with water-soluble organic solvents having boiling points not higher than 230° C, along with a polymeric dispersant, to enhance drying rate, image durability, and redispersibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low-boiling point water-soluble organic solvents are added to improve volatility and drying rate, then drying rate is improved, but jetting reliability deteriorates due to fast drying and nozzle clogging
Solution Approach 1:
The patent changes the chemical composition parameters of the ink by introducing a specific polyurethane polymer with controlled molecular weight (10,000-100,000 g/mol) and functional groups. This polymer modifies the ink's volatility characteristics and drying behavior, allowing faster drying without the harmful effects of low-boiling point solvents alone.
Solution Approach 2:
The patent creates a composite ink formulation combining water, high-boiling point solvents (boiling point >230°C), and a specifically designed polyurethane polymer. This composite system achieves synergistic effects where the polymer provides controlled volatility and adhesion while the solvent mixture maintains jetting reliability and prevents nozzle clogging.
2Productivity
If polymeric binders are added to reduce solvent loading and achieve faster drying, then drying rate is improved, but jetting reliability deteriorates due to film formation and nozzle plugging
Solution Approach 1:
The patent precisely controls the polymer's molecular weight (10,000-100,000 g/mol) and functional group content to optimize the balance between drying rate and jetting reliability. This parameter control prevents excessive film formation that would cause nozzle plugging while maintaining sufficient adhesion for fast drying.
Solution Approach 2:
The patent introduces specific functional groups (carboxyl, hydroxyl, amine) at controlled concentrations within the polyurethane polymer structure. These localized functional groups provide specific interactions with substrates and other ink components, enabling controlled drying behavior without excessive polymer film formation that would plague nozzles.
3Productivity
If solvent loading is reduced to achieve faster drying, then drying rate is improved, but image durability deteriorates
Solution Approach 1:
The patent formulates a composite ink system where the polyurethane polymer acts as a binder that provides both adhesion for fast drying and film integrity for image durability. The polymer matrix traps pigment particles and forms a durable film even with reduced solvent loading, preventing image smudging and smearing.
Solution Approach 2:
The patent adjusts the polymer concentration and molecular weight parameters to achieve optimal film formation at reduced solvent levels. The controlled polymer structure ensures sufficient binding strength and film continuity to maintain image durability despite lower solvent content that enables faster drying.
4Productivity
If ink is formulated for fast drying on low and non-absorption substrates, then drying rate is improved, but redispersibility deteriorates
Solution Approach 1:
The patent introduces specific functional groups (carboxyl, hydroxyl, amine) at controlled concentrations within the polyurethane polymer. These localized polar groups maintain hydrophilicity and redispersibility even after fast drying, allowing the dried ink to be easily redispersed in water without requiring excessive mechanical energy or additional chemicals.
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 proposed ink composition achieves faster drying, improved image durability, and reliable jetting performance on low and non-absorption substrates, addressing the limitations of existing inkjet inks.
Implementation Method 1
the aqueous vehicle comprising one or more water soluble organic solvents with boiling points lower than 230° C. at ambient atmospheric pressure
Data Source
AI summary
The present disclosure pertains to an aqueous inkjet ink containing a pigment as colorant, a polymeric dispersant, a polyurethane binder, and an aqueous vehicle. The inks show improved properties for printing on low and non-absorption substrates.