Vinyl Ester Latex for Non-Wovens via In-Situ Stabilization
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Solution Overview
Problem
Vinyl acetate/ethylene emulsion polymers used for bonding non-wovens suffer from unacceptable loss in strength when exposed to water or organic solvents, short shelf life, and insufficient adhesion, limiting their commercial and industrial applications, and the use of surfactants and protective colloids can lead to environmental issues and increased costs.
Innovation Solution
A vinyl ester based polymer latex composition is developed through free radical emulsion polymerization in the substantial absence of a protective colloid and with minimal surfactant content, using a monomer composition that includes vinyl ester, ethylene, and post-crosslinking monomers, achieving high solid content and improved colloidal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If surfactants and protective colloids are used to stabilize vinyl acetate/ethylene emulsion polymers, then colloidal stability and shelf life are improved, but environmental problems arise and costs increase
Solution Approach 1:
The patent removes surfactants and protective colloids from the emulsion polymerization system entirely. Instead of adding external stabilizing agents, the invention uses a protective colloid formed in-situ during polymerization through the polymerization of unsaturated carboxylic acid and hydrophilic co-monomer, which stabilizes the latex without requiring external surfactants or protective colloids.
Solution Approach 2:
The system stabilizes itself through the formation of a protective colloid during the polymerization process. The unsaturated carboxylic acid and hydrophilic co-monomer polymerize to form a stabilizing structure that emerges from the system itself, eliminating the need for external stabilizing agents and reducing environmental impact.
2Strength
If conventional vinyl acetate/ethylene emulsion polymers are used for bonding non-wovens, then adhesion is provided, but unacceptable loss in strength occurs when exposed to water or organic solvents
Solution Approach 1:
The patent creates a composite polymer structure by copolymerizing vinyl acetate with ethylene and unsaturated carboxylic acid, and crosslinking with N-methylol acrylamide. This composite structure combines the adhesive properties of vinyl acetate with the stability of crosslinked networks and the hydrophilicity of the carboxylic acid groups, providing both adhesion and strength retention in wet conditions.
Solution Approach 2:
The invention modifies the chemical composition parameters of the polymer by incorporating unsaturated carboxylic acid and hydrophilic co-monomers into the vinyl acetate/ethylene copolymer structure. This changes the polymer's properties to improve water and solvent resistance while maintaining adhesion, addressing the reliability issue.
3Ease of manufacture
If conventional vinyl acetate/ethylene emulsion polymers are used, then bonding is provided, but unacceptably short shelf life and lack of latex stability occur
Solution Approach 1:
The patent performs preliminary stabilization during the polymerization process by forming a protective colloid structure in-situ. This preliminary action of creating the stabilizing structure during synthesis prevents degradation and extends shelf life before the product is even applied, rather than relying on post-manufacturing additives.
4Stability of the object's composition
If protective colloid is added to stabilize the latex composition, then colloidal stability is improved, but system complexity increases and costs increase
Solution Approach 1:
The patent extracts the need for external protective colloids by generating the stabilizing structure internally during polymerization. The unsaturated carboxylic acid and hydrophilic co-monomer form the protective colloid structure as part of the polymerization process itself, eliminating the need to add separate protective colloid materials and simplifying the system.
Solution Approach 2:
The unsaturated carboxylic acid and hydrophilic co-monomer serve multiple functions: they are monomers that form the polymer structure, and simultaneously they form the protective colloid that stabilizes the latex. This multi-functionality eliminates the need for separate stabilizing agents, reducing system complexity.
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 resulting latex composition provides enhanced wet tensile strength and stability to non-woven products, reducing the need for surfactants and protective colloids, thus addressing environmental concerns and cost issues while improving performance.
Implementation Method 1
obtainable by free radical emulsion polymerization of a vinyl ester monomer, an ethylene monomer and a post-crosslinking monomer
Data Source
AI summary
The present invention relates to a vinyl ester based polymer latex composition obtainable by free radical emulsion polymerization in substantial absence of a protective colloid and in the presence of no or small amounts of a surfactant, and to a process of making the same. The invention further pertains to a dispersion incorporating said vinyl ester based polymer latex composition, products comprising said dispersion, and various uses of the dispersion.