Absorbent article with graphics printed in preservative-free ink, and methods of manufacture thereof
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Solution Overview
Problem
There is a need for water-based ink formulations suitable for inkjet or CIJ printing processes that are substantially free of traditional preservatives, while maintaining stability and preventing microbial growth, to address regulatory concerns and consumer preferences in personal hygiene products.
Innovation Solution
The development of aqueous inkjet ink compositions that use polymer-dispersed pigment colorants, solvo-surfactants like 2-phenoxyethanol, and antimicrobial agents to inhibit microbial growth without relying on traditional preservatives, ensuring stability and compatibility with printing equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional preservatives are used in water-based ink formulations, then microbial growth is inhibited and shelf life is extended, but consumer acceptance decreases and regulatory concerns increase
Solution Approach 1:
The patent removes traditional preservatives from the ink formulation and replaces them with alternative antimicrobial mechanisms including solvo-surfactants (2-phenoxyethanol), antimicrobial peptides (nisin, lactocin), and bacteriophage-based systems. This extraction of harmful preservatives while maintaining protective functions directly resolves the contradiction between shelf life and consumer acceptance.
Solution Approach 2:
The patent fundamentally changes the chemical parameters of the ink system by transitioning from preservative-based protection to alternative mechanisms such as pH adjustment (using buffers like phosphate or citrate), ionic strength modification, and the introduction of natural antimicrobial agents. These parameter changes enable microbial inhibition without traditional preservatives, addressing both reliability and consumer acceptance.
2Object-generated harmful factors
If water-based inks are used to reduce VOC emissions, then environmental compliance is improved, but microbial contamination risk increases
Solution Approach 1:
The patent introduces intermediary substances that mediate between the water-based ink medium and microbial contamination prevention. These include solvo-surfactants like 2-phenoxyethanol that provide antimicrobial protection, pH buffers that create unfavorable conditions for microbes, and natural antimicrobial peptides. These intermediaries enable water-based inks to maintain both environmental compliance and microbial safety.
Solution Approach 2:
The patent creates composite ink formulations that combine water-based carriers with multiple functional components including solvo-surfactants, antimicrobial peptides, pH buffers, and chelating agents. This composite approach integrates environmental compliance with microbial contamination prevention, resolving the contradiction between reduced VOC emissions and microbial safety.
3Adaptability or versatility
If preservative-free ink formulations are developed to meet consumer preferences, then product appeal increases, but ink stability and microbial resistance decrease
Solution Approach 1:
The patent implements preliminary protective measures in the ink formulation by pre-adjusting pH to optimal ranges (6.5-7.5 for cyan, 7.5-8.5 for magenta, 8.5-9.5 for yellow, 9.5-10.5 for black), adding chelating agents to bind metal ions that could catalyze degradation, and incorporating antimicrobial peptides before the ink is subjected to storage or printing conditions. These preliminary actions ensure stability and microbial resistance are built into the formulation itself, maintaining both consumer preference and ink stability.
Solution Approach 2:
The patent enables the ink system to self-regulate and self-protect through built-in mechanisms such as pH buffer systems that automatically resist pH changes, chelating agents that continuously bind metal ions, and antimicrobial peptides that actively inhibit microbial growth. This self-service capability maintains ink stability without requiring traditional preservatives, satisfying both consumer preferences and stability requirements.
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 ink compositions effectively prevent microbial growth and maintain stability, meeting regulatory standards and consumer preferences by using polymer-dispersed pigments and solvo-surfactants, ensuring the ink's suitability for high-speed printing processes without the need for traditional preservatives.
Implementation Method 1
aqueous inkjet ink compositions... that are substantially free of traditional preservatives, while having features that preserve and/or enhance shelf life by inhibiting microbe growth
Implementation Method 2
polymer-dispersed pigment colorants
Data Source
AI summary
Absorbent articles having components bearing graphics printed using particular inkjet ink compositions and fluid sets are disclosed. The aqueous inkjet ink compositions may include a composition consisting of one or more compounds represented by the following Structure I:HO—CH2-CH2-R (I)wherein R may be a substituted or unsubstituted phenyl group or a substituted or unsubstituted phenoxy group. Printed regions of components of the articles may bear deposits of dried ink including constituents of the disclosed compositions, that include the one or more Structure I compound(s). The presence of the Structure I compounds in the printed regions may have an effect of inhibiting bacterial growth thereon.