Hydroxyl Monomer Adhesive Prevents Chelate Formation
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Solution Overview
Problem
Aqueous adhesives face issues with chelate formation due to acrylic acid and ionic impurities, leading to reduced adhesion and peel strength over time, particularly with increased gel content, which existing technologies struggle to mitigate effectively.
Innovation Solution
Incorporating a hydroxyl group-containing monomer instead of acrylic acid in the aqueous adhesive composition prevents chelate formation, maintaining adhesion and peel strength stability over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If acrylic acid is used as a functional monomer to impart high peel strength and cohesion, then adhesion is improved, but chelate formation with ionic impurities increases gel content causing reduction in adhesion over time
Solution Approach 1:
The patent changes the chemical parameter of the functional monomer from acrylic acid to hydroxyl group-containing monomer (such as hydroxyethyl acrylate or hydroxypropyl methacrylate). This parameter change eliminates the carboxyl group that forms chelates with ionic impurities, thereby preventing gel content increase and maintaining adhesion stability over time while preserving initial adhesion performance
Solution Approach 2:
The patent extracts and removes the problematic carboxyl group functionality from the monomer structure. By using hydroxyl group-containing monomers instead of acrylic acid, the invention removes the source of chelate formation while retaining the essential adhesive functionality through the hydroxyl group, thus solving the adhesion stability problem
2Stability of the object's composition
If low-ionic emulsion polymerization is performed to prevent chelate formation, then adhesion stability is improved, but polymerization stability deteriorates causing agglomerate generation and productivity reduction
Solution Approach 1:
The patent changes the monomer parameter from acrylic acid to hydroxyl group-containing monomer, which fundamentally alters the chemical reactivity profile. This change allows the use of standard ionic emulsion polymerization conditions without chelate formation issues, thereby maintaining both polymerization stability (preventing agglomerates) and adhesion stability (preventing gel content increase), thus resolving the productivity conflict
Solution Approach 2:
The hydroxyl group-containing monomer acts as an intermediary that bridges the conflicting requirements. It provides the necessary adhesive functionality without the harmful chelating property of acrylic acid, allowing conventional ionic polymerization systems to operate efficiently without producing agglomerates or compromising long-term adhesion stability
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 use of a hydroxyl group-containing monomer in the aqueous adhesive composition prevents chelate formation, ensuring minimal change in adhesion and peel strength, even with increased gel content, thereby maintaining adhesive performance.
Implementation Method 1
acrylic acid reacts with ionic impurities included in initiators, emulsifiers, neutralizers and thickeners to form a chelate after polymerization. Such a chelate increases gel content, causing increase in hardness and reduction in adhesion of adhesives
Data Source
Figure 1
AI summary
Disclosed is an aqueous adhesive composition, the adhesive properties of which are barely degraded due to aging. The aqueous adhesive composition according to the present invention has the technical features of comprising a monomer having a hydroxyl group, and of not forming a chelate compound after polymerization. Thus, the aqueous adhesive composition has the advantages of having little reduction in adhesive properties thereof due to an increase in gel content.