Cationic Polyurethane Dispersions via Methanesulfonic Acid Salification
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Solution Overview
Problem
Existing aqueous dispersions of film-forming cationic polyurethanes face challenges in balancing components for good dispersibility, stability in water, and elasticity, which limits their availability and performance in cosmetic and industrial applications.
Innovation Solution
The use of aliphatic diisocyanates and methanesulfonic acid as a salifying agent for tertiary amine groups in the polymer preparation process, achieving a stable and transparent film with improved storability and gloss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional salifying agents are used for cationic polyurethanes, then dispersibility in water is achieved, but stability and storability are insufficient
Solution Approach 1:
The invention changes the chemical parameter of the salifying agent from conventional options (such as hydrochloric acid, sulfuric acid, or organic sulfonic acids) to methanesulfonic acid specifically. This parameter change results in remarkably stable aqueous dispersions with improved storability while maintaining good dispersibility. The patent demonstrates that this specific chemical substitution resolves the contradiction between dispersibility and stability/storability.
2Reliability
If film-forming cationic polyurethanes are prepared for cosmetic use, then hair fixative properties are achieved, but formaldehyde residues from alternative resins create regulatory issues
Solution Approach 1:
The invention extracts and eliminates the harmful formaldehyde component from the system by replacing ureaformaldehyde resins with cationic film-forming polyurethanes. This substitution removes the source of formaldehyde residues while maintaining the desired cosmetic performance for hair fixatives, directly addressing the regulatory concerns about harmful substances in personal care products.
3Ease of operation
If aqueous dispersions are formulated for good dispersibility, then ease of application is improved, but film transparency and gloss are reduced
Solution Approach 1:
The invention changes the chemical parameter of the salifying agent to methanesulfonic acid, which optimizes the balance between dispersibility and film quality. This specific chemical substitution enables the formulation to achieve both good aqueous dispersibility for easy application and enhanced film transparency and gloss, resolving the contradiction between ease of operation and optical properties.
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 combination of aliphatic diisocyanates with methanesulfonic acid results in remarkably stable aqueous dispersions with enhanced transparency and gloss of the films, improving storability and performance in cosmetic and industrial applications.
Implementation Method 1
reacting one or more aliphatic diisocyanates with an aliphatic tertiary amine having two hydroxyl groups that react with -NCO groups and a linear polyol to obtain a prepolymer
Implementation Method 2
salifying with methanesulfonic acid the amine groups of the prepolymer
Data Source
AI summary
Stable aqueous dispersions of film-forming cationic polyurethanes are prepared by extending with water or amines a cationic prepolymer obtained from aliphatic diisocyanates, aliphatic tertiary amines having two hydroxyl groups that react with -NCO groups, linear polyols and methanesulfonic acid.