Water-Dispersible Polyurethane Acrylic Copolymer Emulsion
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Solution Overview
Problem
Traditional aqueous polyurethane and acrylic emulsions suffer from poor stability, high production costs, and material shortcomings such as brittleness at low temperatures and tackiness at high temperatures, along with poor wettability, water resistance, and weathering resistance.
Innovation Solution
A method of synthesizing a polyurethane acrylic copolymer emulsion through copolymerization involving 2-8 wt% isocyanate, 7-15 wt% polyol, and 0.3-1.0 wt% polyol bearing hydrophilic carboxylic monomer, followed by neutralization and emulsion polymerization with alkyl methacrylate or acrylate monomers, using a persulfate initiator, to create a high molecular weight, eco-friendly, solventless emulsion with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional direct emulsification method is used to form aqueous polyurethane emulsion, then the process is simple, but the stability of the emulsion is poor
Solution Approach 1:
The patent applies preliminary action by first forming a polyurethane prepolymer with hydrophilic carboxylic monomer before emulsification. This pre-modification ensures the polymer chains have inherent water dispersibility and stability, eliminating the need for complex multi-step emulsification processes while achieving stable aqueous emulsion formation.
Solution Approach 2:
The patent uses composite materials by combining polyurethane backbone with hydrophilic carboxylic monomer units and acrylic graft chains. This composite structure integrates the mechanical properties of polyurethane with the water resistance and weathering properties of acrylic, while the hydrophilic groups ensure aqueous dispersibility and stability without requiring complex emulsification processes.
2Manufacturing precision
If multi-step procedure (de-emulsification, washing, dehydration, drying) is used to produce solid polymer from acrylic emulsion, then the polymer purity is improved, but the production cost increases and impurities remain difficult to remove
Solution Approach 1:
The patent extracts the problematic multi-step separation process by designing a one-step emulsion polymerization system where the polymer forms directly in aqueous emulsion with inherent stability. The hydrophilic carboxylic monomer and graft structure prevent aggregation and facilitate direct formation of stable emulsions that can be processed without costly de-emulsification, washing, and dehydration steps.
Solution Approach 2:
The patent eliminates the need for expensive multi-step processing by using a simple one-step emulsion polymerization method. The acrylic monomer and initiator system allows direct formation of stable emulsions that can be processed immediately without requiring costly separation equipment and procedures, significantly reducing production costs while maintaining polymer quality.
3Strength
If polyurethane is used for non-polar base materials, then excellent low temperature flexibility and wear resistance are achieved, but wettability, water resistance, and weathering resistance are poor
Solution Approach 1:
The patent applies local quality by introducing hydrophilic carboxylic monomer units at specific locations within the polyurethane chains. These localized hydrophilic groups provide water resistance and weathering properties without compromising the overall polyurethane backbone structure that provides mechanical strength and low-temperature flexibility. The graft acrylic chains further enhance water resistance at the surface level.
Solution Approach 2:
The patent uses composite materials by creating a polyurethane-acrylic graft copolymer system where the polyurethane backbone provides mechanical properties and the grafted acrylic chains with hydrophilic groups provide water resistance and weathering resistance. This composite structure allows simultaneous achievement of both mechanical strength and environmental resistance that neither component could provide alone.
4Object-affected harmful factors
If acrylic emulsion is used to improve water resistance and weathering resistance, then these properties are enhanced, but the material becomes brittle at low temperatures and tacky at high temperatures
Solution Approach 1:
The patent merges the advantages of polyurethane and acrylic by creating a graft copolymer system where polyurethane provides low-temperature flexibility and wear resistance, while grafted acrylic chains provide water resistance and weathering resistance. The combination eliminates the brittleness issue of pure acrylic at low temperatures while maintaining water resistance, and the polyurethane backbone prevents tackiness at high temperatures.
Solution Approach 2:
The patent applies parameter changes by controlling the glass transition temperature through the specific combination of polyol, isocyanate, and acrylic monomer ratios. By adjusting these parameters, the copolymer achieves optimal balance between low-temperature flexibility and high-temperature stability, preventing both brittleness and tackiness while maintaining water resistance and weathering resistance.
5Strength
If high molecular weight polymer is synthesized through emulsion polymerization, then the polymer properties are improved, but the emulsion stability becomes more difficult to maintain
Solution Approach 1:
The patent applies preliminary action by first forming polyurethane prepolymer with hydrophilic carboxylic monomer before adding acrylic monomer for graft polymerization. This pre-formed prepolymer structure provides inherent stability and prevents aggregation during the subsequent graft polymerization, allowing high molecular weight polymer synthesis while maintaining emulsion stability without requiring extensive stabilization procedures.
Solution Approach 2:
The patent uses the hydrophilic carboxylic monomer as an intermediary that bridges the polyurethane backbone and grafted acrylic chains. This intermediary structure ensures proper spacing and distribution of polymer chains in the emulsion, preventing aggregation and maintaining stability even at high molecular weights. The hydrophilic groups act as spacers that prevent chain-chain aggregation while allowing high molecular weight polymer formation.
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 emulsion exhibits excellent low temperature flexibility, wear resistance, water resistance, weathering resistance, and strong wettability, with high extensibility and tensile strength, and superior storage stability, addressing the shortcomings of traditional polyurethane and acrylic emulsions.
Implementation Method 1
2-8 wt% of isocyanate and 7-15 wt% of a polyol, 0.3-1.0 wt% of a polyol bearing hydrophilic carboxylic monomer and 0.1-2.0 wt% of an acrylic ester containing a hydroxyl group reacted to form an unsaturated double bond bearing aqueous polyurethane prepolymer
Implementation Method 2
the hydroxyl group of the acrylic ester containing a hydroxyl group can polymerize with isocyanate and cause the prepolymer to bear an unsaturated double bond
Implementation Method 3
0.1-2.0 wt% of a persulfate initiator was used to carry out emulsion polymerization
Implementation Method 4
side grafting an acrylic monomer to a water-dispersible PU long chain to enable providing a pollution-free water-dispersible PU copolymer acrylic emulsion
Implementation Method 5
0.3-1.0 wt% of a polyol bearing hydrophilic carboxylic monomer... causing the prepolymer to disperse in water
Implementation Method 6
introducing 0.3-1.0 wt% of an alkalic neutralizer to carry out a neutralization reaction
Data Source
AI summary
The present invention provides a method for preparing aqueous emulsion via water dispersible polyurethane grafted acrylate copolymerization, which first uses 2-8 wt % of isocyanate, 7-15 wt % of a polyol, 0.3-1.0 wt % of a polyol bearing hydrophilic carboxylic monomer, and 0.1˜2.0 wt % of an acrylic ester containing a hydroxyl group to cause a reaction and form an unsaturated double bond bearing polyurethane prepolymer, the NCO content of which is approximately 2˜8%. This is followed by introducing 0.3-1.0 wt % of an alkalic neutralizer to carry out a neutralization reaction, and then 25-40 wt % of pure water is used to effect water dispersion, after which 0.1˜0.5 wt % of a chain extender is added to form an ethylenically unsaturated water dispersible polyurethane prepolymer. A reaction system is formed by adding 40-60 wt % of deionized water, 20˜30 wt % of methyl methacrylate or an acrylate monomer to the ethylenically unsaturated water dispersible polyurethane prepolymer, and 0.1˜2.0 wt % of a persulfate is used as an initiator to carry out emulsion polymerization. The aqueous emulsion via water dispersible polyurethane grafted acrylate copolymerization thus obtained is an eco-friendly solventless and pollution-free aqueous resin, and has a high molecular weight, a specific gravity of 1.03˜1.07, which is slightly greater than that of water, excellent storage stability, good permeability, and is easily worked with. The water resistance of a dried coating of the aqueous emulsion is good, and also has high extensibility, excellent tensile strength, good adhesion, and superior wear resistance.