Wash-Off Label Adhesive With Rosin Ester for Low-Temperature Recycling
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Solution Overview
Problem
Existing wash-off labels are inefficient in low temperature washing processes, particularly for filmic and paper labels, and there is a need for labels that can be easily removed during recycling or reuse without the use of high temperatures and alkaline agents.
Innovation Solution
A pressure-sensitive wash-off label comprising a face made of thermoplastic film or paper and a pressure sensitive adhesive layer with a wash-off additive containing a resinous material and a grafted rosin ester, which improves adhesion properties and allows for efficient removal at lower temperatures, such as 65-75°C for filmic labels and 40°C for paper labels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional pressure sensitive adhesives are used in wash-off labels, then the label adheres well to the container surface, but the label cannot be easily removed during low temperature washing processes
Solution Approach 1:
The patent modifies the chemical composition parameters of the pressure sensitive adhesive by incorporating specific resinous materials (rosin, coumarone-indene, styrene-butadiene) and adjusting the ratio of acidic to basic groups. This chemical parameter change enables the adhesive to maintain strong initial adhesion while becoming easily removable under washing conditions through controlled chemical reactions with alkaline washing solutions.
Solution Approach 2:
The patent creates a composite adhesive system combining multiple resinous materials with complementary properties: rosin provides acidic groups for chemical reaction with alkaline wash solutions, coumarone-indene enhances adhesion strength, and styrene-butadiene adds flexibility. This composite formulation achieves both strong adhesion and easy washability that single materials cannot provide.
2Ease of operation
If high washing temperatures are used to remove labels, then the label can be effectively washed off, but energy consumption increases and environmental friendliness decreases
Solution Approach 1:
The patent changes the chemical reactivity parameters of the adhesive by incorporating resinous materials with specific functional groups that react at lower temperatures. The acidic groups in the resinous materials react with alkaline washing solutions at temperatures as low as 40-60°C, enabling effective label removal without high energy input and reducing washing temperature requirements.
Solution Approach 2:
The patent replaces thermal-mechanical removal (high temperature heating) with chemical-mechanical removal (alkaline solution reaction). Instead of relying on high temperature to break adhesive bonds, the adhesive is designed to undergo controlled chemical reactions with alkaline washing solutions, enabling effective label removal at lower temperatures through chemical rather than purely thermal mechanisms.
3Ease of operation
If alkaline agents are used to facilitate label removal, then washability improves, but environmental impact and processing complexity increase
Solution Approach 1:
The patent adjusts the pH sensitivity parameters of the adhesive by incorporating resinous materials with controlled acidic group content. This enables the adhesive to be specifically designed to react with mild alkaline solutions, allowing effective label removal with environmentally friendlier, lower concentration alkaline agents rather than requiring strong chemicals.
Solution Approach 2:
The patent designs the adhesive as a disposable, single-use component that is intentionally made easy to remove and dispose of after its labeling function is complete. The adhesive is formulated to completely wash off with mild alkaline solutions, creating no persistent residue and enabling simple disposal without complex environmental remediation, effectively treating the adhesive as a temporary, low-impact consumable.
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 label achieves improved washability and reduced washing time, enabling efficient removal of labels from containers while maintaining environmental friendliness and cost-effectiveness, with the adhesive remaining attached to the face during the process.
Implementation Method 1
a pressure sensitive adhesive layer for adhering the label to a surface of an item to be labelled
Data Source
AI summary
The invention relates to a method for manufacturing a label (2) comprising a face (1) and a pressure sensitive adhesive layer (4), wherein the method comprises steps of applying an acrylic adhesive onto a first surface of the face (1), wherein the acrylic adhesive comprises a wash-off additive comprising a resinous material and a grafted rosin ester, and drying the acrylic adhesive in order to form an acrylic pressure sensitive adhesive onto the first surface of the face (1), thereby obtaining the label (2). The invention further relates to a label comprising a face (1) and a pressure sensitive adhesive layer (4), wherein the acrylic adhesive comprises a wash-off additive comprising a resinous material and a grafted rosin ester.