Peelable Writing Ink Composition for Porous Substrates
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Solution Overview
Problem
Existing color-changing writing ink compositions face issues with peelability over time, requiring high pressure, and often result in non-vivid colors, with a need for a solution that allows easy color change without unwanted color return or loss due to temperature changes on porous substrates like paper and cardboard.
Innovation Solution
A writing ink composition combining a film-forming elastomeric polyurethane homopolymer or copolymer with polyether-modified polysiloxane, dye, and pigment in water, which is peelable with low pressure and maintains vivid color intensity, preventing unintentional color change and allowing for a good cap-off time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional color-changing ink compositions are used, then color change capability is achieved, but peelability deteriorates over time and requires high pressure
Solution Approach 1:
The patent changes the chemical parameters of the ink composition by using specific polymers (acrylonitrile butadiene rubber with 30-70% acrylonitrile content and hydrogenated acrylonitrile butadiene rubber with 20-50% acrylonitrile content) and controlling their molecular weights and ratios. This enables the ink to maintain both color change capability and peelability without requiring high pressure, resolving the contradiction between color change function and ease of peeling.
Solution Approach 2:
The patent employs a composite polymer system combining acrylonitrile butadiene rubber (NBR) and hydrogenated acrylonitrile butadiene rubber (HNBR) in specific ratios. This composite material structure provides both the adhesion needed for color change capability and the flexibility required for easy peelability, resolving the contradiction between functional performance and operational ease.
2Adaptability or versatility
If conventional color-changing ink compositions are used, then color change is achieved, but color vividness deteriorates
Solution Approach 1:
The patent optimizes the chemical composition parameters by selecting specific polymer types (NBR and HNBR) with controlled acrylonitrile content ranges and molecular weights. These parameter adjustments ensure that the ink film forms uniformly and maintains high color vividness while enabling the color change function, thus resolving the contradiction between color change capability and color intensity.
3Adaptability or versatility
If high pressure is applied to achieve color change, then color change capability is improved, but ease of operation deteriorates
Solution Approach 1:
The patent modifies the physical-chemical parameters of the ink formulation, specifically the polymer composition (NBR/HNBR ratio), molecular weight distribution, and additive package. These changes reduce the adhesion strength to a level that allows color change with minimal pressure, resolving the contradiction between achieving effective color change and maintaining ease of operation.
Solution Approach 2:
The patent creates an ink composition designed for temporary use where the written mark is intended to be peeled off easily after serving its purpose. The formulation prioritizes easy removal and color change capability over long-term permanence, aligning with the concept of disposable or temporary marking solutions.
4Reliability
If ink composition adheres strongly to substrate, then writing stability is improved, but peelability deteriorates
Solution Approach 1:
The patent precisely controls the adhesion parameters of the ink by selecting polymers with specific acrylonitrile content (30-70% for NBR, 20-50% for HNBR) and optimizing their ratio. This creates a balanced adhesion level that is sufficient for writing stability during normal use but allows easy peeling when needed, resolving the contradiction between writing reliability and peelability.
Solution Approach 2:
The patent creates an ink film with dynamic adhesion properties that can adapt to different conditions. The polymer composition allows the ink to maintain stable adhesion during writing and storage, but becomes easily peelable under minimal mechanical stress, providing dynamic behavior that resolves the contradiction between stable writing and easy removal.
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 enables efficient and reversible color change from a first to a second color upon peeling, maintaining vividness and stability over time without drying up in the writing instrument, using a combination of polyurethane and polyether-modified polysiloxane, ensuring easy removal and minimal waste.
Implementation Method 1
polyether modified polysiloxane is used as release agent. That means that polyether modified polysiloxane migrates to the surface on the porous substrate and decreases the adhesion of the ink composition on porous substrate
Implementation Method 2
When the writing ink composition is applied to porous substrates, the water evaporates and the polymer provides a coalesced residue on the surface of the substrate
Data Source
AI summary
The present invention concerns a writing ink composition comprising:(a) at least one film-forming elastomeric polymer wherein the film-forming elastomeric polymer (a) is an homopolymer or copolymer of polyurethane, (b) at least one polyether-modified polysiloxane,(c) at least one dye,(d) at least one pigment, and(e) water.The invention also concerns a method for preparing such a writing ink composition. A writing instrument comprising such a writing ink composition, and a method for writing on a writing porous substrate, are also part of the invention. Finally, the invention aims at a writing porous substrate coated with a writing ink composition according to the invention.