Vinyl Acetate Emulsion Adhesive Stability
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Solution Overview
Problem
Aqueous vinyl acetate polymer emulsions used in adhesives face challenges with storage stability and viscosity, leading to adverse effects on bond strength and heat seal performance, which are often mitigated by increasing surfactants or adding protective colloids, but these solutions are not economically viable and can cause foaming or high viscosity.
Innovation Solution
An aqueous vinyl acetate polymer emulsion with a composition of 20-80% vinyl acetate, 20-80% α,β-ethylenically unsaturated carboxylic ester monomer, 0.1-5% stabilizer monomer, and 0.05-1% surfactant, excluding protective colloids, resulting in low viscosity and improved storage stability, applied in an adhesive composition for laminates and textile applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of surfactants is increased to improve emulsion storage stability, then storage stability is improved, but viscosity increases and foaming occurs which deteriorates adhesive performance
Solution Approach 1:
The patent changes the chemical composition parameters by introducing specific functional monomers (carboxylic acid monomers and hydroxyl-containing monomers) that modify the polymer chain properties. This allows achieving storage stability through chemical structure modification rather than increasing surfactant concentration, thereby avoiding foaming and excessive viscosity
Solution Approach 2:
The patent creates a composite polymer structure by copolymerizing vinyl acetate with multiple functional monomers (carboxylic acid monomers and hydroxyl-containing monomers). This composite material approach provides both storage stability and low viscosity through the synergistic effects of different functional groups within the polymer chain
2Reliability
If protective colloids such as PVOH and HEC are added to improve storage stability, then storage stability is improved, but viscosity increases which deteriorates adhesive performance
Solution Approach 1:
The patent modifies the polymer composition by incorporating carboxylic acid monomers and hydroxyl-containing monomers that provide protective colloidal effects within the polymer chain itself. This eliminates the need for separate protective colloid additives that would increase viscosity, achieving both stability and low viscosity through internal functional groups
Solution Approach 2:
The patent extracts the protective colloid function from separate additive materials (PVOH, HEC) and integrates it directly into the polymer structure through copolymerization of functional monomers. This consolidation provides protective colloid benefits without the viscosity penalty of adding separate high-molecular-weight protective colloids
3Ease of manufacture
If vinyl acetate monomer is used to achieve low cost and high water solubility, then cost is reduced and water solubility is improved, but storage stability deteriorates
Solution Approach 1:
The patent creates a composite copolymer system where vinyl acetate (提供低成本和高水溶性) is combined with carboxylic acid monomers and hydroxyl-containing monomers (提供存储稳定性). The synergistic interaction between these components achieves both cost-effectiveness and storage stability simultaneously
Solution Approach 2:
The patent optimizes the compositional parameters by controlling the ratios of vinyl acetate to functional monomers, and the degree of polymerization. By adjusting these parameters, the patent achieves the desired balance between cost (vinyl acetate content) and storage stability (functional monomer content)
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 solution achieves acceptable emulsion storage stability, low viscosity, and enhanced adhesive performance, including strong bond strength and heat seal strength, without the drawbacks of high surfactant levels or protective colloids, thus optimizing the use of vinyl acetate polymer emulsions in adhesive compositions.
Implementation Method 1
The steric hindrance provided by the stabilizer monomer units in the polymer chain helps to prevent polymer chain aggregation
Implementation Method 2
from 0.05% to 1% by dry weight, based on total dry weight of the polymer, of a surfactant
Data Source
AI summary
An aqueous polymer emulsion comprising: i) as polymerized units, from 20％ to 80％ by dry weight, based on total dry weight of the polymer, of vinyl acetate; ii) as polymerized units, from 20％ to 80％ by dry weight, based on total dry weight of the polymer, of an α, β-ethylenically unsaturated carboxylic ester monomer; iii) as polymerized units, from 0.1％ to 5％ by dry weight, based on total dry weight of the polymer, of a stabilizer monomer; iv) from 0.05％ to 1％ by dry weight, based on total dry weight of the polymer, of a surfactant, wherein said aqueous polymer emulsion has a viscosity of less than 100cps. An aqueous adhesive composition comprising said aqueous polymer emulsion.