Aqueous Inkjet Inks for Textiles Using Crosslinkable Polyurethane
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Solution Overview
Problem
Aqueous inkjet ink compositions used for printing on textiles face challenges in maintaining color fastness and durability, particularly after multiple launderings and abrasive uses, with existing solutions failing to adequately address light fastness and wash fastness.
Innovation Solution
The development of an aqueous inkjet ink composition incorporating a non-crosslinked, crosslinkable polyurethane derived from an aromatic diisocyanate and a diol mixture, combined with a dispersed pigment colorant and humectant, which can be crosslinked after application to enhance wash and color fastness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pigment-based inks are used for textile printing, then the ink can be applied to various substrates, but the color fastness and wash durability are insufficient after repeated laundering
Solution Approach 1:
The patent modifies the chemical parameters of the polyurethane binder by controlling its molecular weight (5,000-50,000), acid number (20-40), and glass transition temperature (0-50°C) to optimize the balance between inkjet printability and post-printing durability. These parameter adjustments enable the binder to form sufficiently strong bonds with textile fibers while maintaining adequate flexibility and adhesion properties.
Solution Approach 2:
The invention creates a composite ink formulation combining pigment particles with a specifically engineered polyurethane binder system. This composite approach integrates the colorant particles within a polymer matrix that provides both initial deposition capability and long-term fastness properties, resulting in a material system that exhibits enhanced wash durability compared to simple pigment suspensions.
2Reliability
If crosslinked polyurethane is used to improve wash fastness, then color fastness improves, but the ink viscosity and printability may be adversely affected
Solution Approach 1:
The patent employs a crosslinkable polyurethane binder that is applied to the textile substrate in a non-crosslinked, low-viscosity state suitable for inkjet deposition. After printing, the binder undergoes crosslinking transformation (through heat treatment or chemical reaction) to form a durable, wash-fast film. This preliminary application in a processable state followed by post-application modification resolves the contradiction between printability and final fastness properties.
Solution Approach 2:
The binder system transitions dynamically from a flexible, low-viscosity non-crosslinked state during printing to a rigid, high-strength crosslinked state after treatment. This temporal transformation allows the material to exhibit appropriate properties at different stages of the printing process: ease of deposition initially, then enhanced durability after crosslinking, effectively resolving the contradiction between operability and performance.
3Reliability
If polyurethane additives are added to pigment-based inks, then durability improves, but the formulation complexity increases
Solution Approach 1:
The patent extracts and isolates the critical binder function into a single, well-defined polyurethane component with specified parameters (molecular weight, acid number, glass transition temperature). Rather than using complex mixtures of multiple polymers and additives, the invention focuses on optimizing one key material system, thereby reducing formulation complexity while maintaining or improving durability performance.
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 composition exhibits improved water fastness and color fastness, maintaining tactile properties and resistance to mechanical abrasion, while ensuring durable and long-lasting inkjet printed images on textiles.
Implementation Method 1
a non-crosslinked, crosslinkable polyurethane... which can be crosslinked after application to enhance wash and color fastness
Data Source
AI summary
Individual aqueous inks or inks in ink sets haves a non-crosslinked, crosslinkable polyurethane having an acid number of 20-40 and is derived from an aromatic diisocyanate; and a diol mixture of D1 and D2 diols, and optionally including D3 diol, D4 diol, or both D3 and D4 diols. D1 has a C3 to C7 aliphatic group and a pendant carboxy group or neutralized carboxy group. D2 has a chain of repeating C2 to C6 alkylene oxide groups. D3 is an alkoxylated bisphenol A or an aliphatic cyclic diol, present at least 5 mol %. D4 is a hydroxy-terminated polybutadiene having a molecular weight of at least 1000 and is present in an amount of 0.1-5 mol %. The ink also contains a dispersed pigment colorant; a humectant or organic co-solvent, and optionally, a crosslinking agent. These aqueous inks can be used for inkjet printing images on textiles.