Aqueous Ionomer Dispersion Stabilization via Cation Segmentation
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Solution Overview
Problem
Ionomers neutralized with multivalent cations or monovalent salts face challenges in forming aqueous dispersions due to crosslinking and increased melt viscosity, making it difficult to disperse them in water effectively.
Innovation Solution
Aqueous ionomer dispersions comprising an ethylene acid copolymer partially neutralized with zinc and monovalent cations, mixed with a polyolefin and water, to create a stable dispersion suitable for coating substrates, with specific composition ranges and neutralization percentages to enhance dispersibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If ionomers are neutralized with multivalent cations, then ionic crosslinking and structural stability are improved, but dispersibility in water deteriorates due to polymeric crosslink formation
Solution Approach 1:
The patent segments the neutralization process by using a two-stage approach: first neutralizing with multivalent cations (Ca2+, Mg2+) to establish ionic crosslinking for stability, then adding monovalent cations (Na+, K+) to break excess crosslinks and improve dispersibility. This segmentation allows both stability and dispersibility to coexist.
Solution Approach 2:
The patent changes the ionic composition parameters by controlling the ratio of multivalent to monovalent cations. Specifically, it maintains multivalent cation content at 0.1-10 mmol/g and monovalent cation content at 1-20 mmol/g, optimizing the balance between crosslinking stability and water dispersibility.
2Ease of manufacture
If ionomers are neutralized with monovalent salts, then dispersibility in water is improved, but melt viscosity increases and hydrophobicity worsens
Solution Approach 1:
The patent segments the cation composition into two functional groups: multivalent cations (Ca2+, Mg2+) that control melt viscosity through controlled crosslinking, and monovalent cations (Na+, K+) that provide water dispersibility. This segmentation allows optimization of both properties simultaneously.
Solution Approach 2:
The patent creates a composite ionic structure combining multiple cation types within the ionomer. The synergistic interaction between multivalent and monovalent cations produces a material that achieves both low melt viscosity (through monovalent cation dominance) and water dispersibility (through balanced ionic composition).
3Reliability
If ionomer composition uses higher acid copolymer content, then coating performance is improved, but formation of stable aqueous dispersion becomes more difficult
Solution Approach 1:
The patent optimizes the acid copolymer content parameter to 10-40 wt% of total polymer, which provides sufficient coating performance while maintaining adequate water dispersibility. Additionally, it controls the cation composition parameters to enable stable aqueous dispersion formation at this acid copolymer level.
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 enables the formation of stable aqueous ionomer dispersions with improved dispersibility and static charge properties, suitable for coating various substrates, including flooring, plastics, and textiles, with enhanced static charge and powder retention performance.
Implementation Method 1
wherein at least 70 mole % of total acid units of the ethylene acid copolymer are neutralized, with from 15 mole % to 50 mole % of total acid units of the ethylene acid copolymer being neutralized with a zinc cation and at least 40 mole % of total acid units of the ethylene acid copolymer being neutralized with a monovalent cation
Data Source
AI summary
An aqueous ionomer dispersion, and method of manufacturing thereof, comprising an ionomer composition and water, wherein the ionomer composition comprises: a) at least 20 wt. %, based on the total weight percent of the ionomer composition, of an ionomer; and b) up to 80 wt. %, based on the total weight percent of the ionomer composition, of a polyolefin.