Self-Adhesive Labels for Moist Surfaces Using pH-Sensitive Polymers
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Solution Overview
Problem
Existing self-adhesive labels face difficulties in application to moist surfaces and cannot be removed without residue at elevated temperatures and alkaline pH values, particularly when used on beverage bottles.
Innovation Solution
A method using a polymer A with a glass transition temperature ≤ -40 °C, produced by radical polymerization, and an aminotriazine compound B, applied in an aqueous medium at temperatures ≥ 50 °C and pH ≥ 7.5, to create a self-adhesive article that can be easily removed without leaving residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If casein-based adhesives are used at temperatures ≤ 20 °C in neutral media, then the adhesive is soluble in aqueous media, but the adhesive cannot be removed without residue at temperatures ≥ 50 °C and pH values ≥ 7.5
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition of the adhesive system. It uses a copolymer containing polar groups (acrylic acid, methacrylic acid, itaconic acid, or maleic acid) combined with specific additives (polyethylene glycol with molecular weight 200-2000 and triethanolamine) to create an adhesive that responds differently to temperature and pH changes. This composition enables the adhesive to remain soluble at low temperatures and neutral pH while becoming removable at elevated temperatures and alkaline pH values.
Solution Approach 2:
The patent employs composite materials by combining multiple components in the adhesive formulation: a copolymer base with polar groups, polyethylene glycol additive, and triethanolamine additive. This composite adhesive system achieves the dual functionality of being soluble in aqueous media under normal conditions while allowing residue-free removal under controlled alkaline and thermal conditions.
2Ease of operation
If pressure-sensitive adhesives are used for labeling, then the adhesive can be applied easily, but the adhesive is difficult to apply to moist surfaces
Solution Approach 1:
The patent modifies the adhesive parameters by incorporating hydrophilic components (polyethylene glycol and triethanolamine) into the copolymer adhesive system. These components enhance the adhesive's compatibility with moist surfaces by adjusting its surface energy and wettability characteristics, allowing effective bonding even when the substrate surface contains moisture.
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 method enables self-adhesive articles to be applied to surfaces at various temperatures and pH levels, including moist conditions, and allows for residue-free removal at elevated temperatures and alkaline pH, suitable for industrial labeling and cleaning processes.
Implementation Method 1
a polymer A obtainable by radical polymerization with a glass transition temperature ≤ -40 °C
Implementation Method 2
the composite is treated with an aqueous medium which has a temperature ≥ 50 ° C and a pH ≥ 7.5
Data Source
AI summary
Method for producing self-adhesive items using a polymer with low glass-transition temperature and an amino triazine compound.