Sprayed Polyurea–Polyurethane Composites for Structural Soundness
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Solution Overview
Problem
Existing methods for producing polyurethane/polyurea composites, particularly for water-holding vessels like sinks and pools, result in brittle and structurally unsound products, despite the potential for quick and cost-effective manufacturing.
Innovation Solution
A method involving the sequential application of four primary layers - aliphatic polyurea, first elastomeric, structural foam, and second elastomeric layers - using specific spray systems with controlled temperature, pressure, and filtration, ensuring each layer's optimal properties and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple polyurethane and polyurea coatings are applied sequentially to a substrate, then the manufacturing process becomes quick and cost-effective, but the resulting composite product becomes brittle and structurally unsound
Solution Approach 1:
The coating process is divided into multiple sequential layers with different compositions and properties. Each layer is applied separately and allowed to cure before the next layer is applied, creating a segmented structure that prevents brittleness while maintaining manufacturing efficiency. The layers include polyurea, polyurethane, and intermediate elastomeric layers, each serving a specific structural function.
Solution Approach 2:
The patent creates a composite coating system combining polyurea, polyurethane, and elastomeric materials in specific layers. This composite structure leverages the fast cure rate and low VOC benefits of polyurea while using polyurethane and elastomeric layers to provide structural flexibility and prevent brittleness, achieving both productivity and reliability.
2Loss of time
If multiple coatings are applied onto a substrate to form a composite product, then the production process is fast and economical, but the composite becomes prone to fracturing
Solution Approach 1:
The patent controls critical parameters including layer thickness (3-12 mils per layer), temperature (70-100°F ambient, 80-120°F spray temperature), pressure (500-2000 psi), and curing time between layers. These controlled parameters ensure proper bonding and flexibility at each interface, preventing fracture while maintaining fast production cycles.
Solution Approach 2:
Elastomeric intermediate layers are introduced between the polyurea and polyurethane layers to act as mediators. These intermediate layers provide flexibility and stress distribution, preventing the brittle fracture that would occur in direct polyurea-polyurethane bonding, while still allowing rapid sequential application.
3Device complexity
If conventional spray systems are used for applying multiple layers, then the process is simple, but the bonding between layers is insufficient and composites are structurally weak
Solution Approach 1:
The patent replaces conventional mechanical spray systems with a heated spray system that controls material temperature and viscosity. The heating elements maintain materials at 80-120°F, optimizing flow characteristics and bonding capability. This thermal control mechanism enhances layer bonding without significantly increasing device complexity.
Solution Approach 2:
The spray system includes pre-heating of materials before application, and the process includes allowing each layer to cure fully before applying the next layer. This preliminary preparation ensures optimal bonding conditions are established before each layer is applied, strengthening the composite structure without complicating the spray system itself.
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
Produces structurally robust and durable composites that are efficiently manufactured, overcoming brittleness issues while maintaining the benefits of fast cure and low VOCs.
Implementation Method 1
These coatings may be formed as the reaction product of an isocyanate component with a resin component, such as a amine or a polyol
Implementation Method 2
Both components can be heated via heating elements in the spray system, such as within hoses that connect reservoirs holding the material components with the spray gun
Implementation Method 3
The isocyanate and resin components can both be sprayed at a material pressure in a range of 1300 psi to 3000 psi
Data Source
AI summary
Polyurea/polyurethane composites and methods for making the same are disclosed. Four primary layers, an aliphatic polyurea layer, a first elastomeric layer, a structural foam layer, and second elastomeric layer, can be applied to a mold sequentially. By using plural component spray systems to spray isocyanate components and resin components corresponding to each layer at specifications, such as the temperatures and pressures of the material components, structurally sound molded composites can be formed. The spray system for the aliphatic polyurea layer can use a liquid or mechanical purge type spray gun, while the spray systems for the first elastomeric layer, the structural layer, and a second elastomeric layer can use air, mechanical or solvent purge type spray guns. Optional layers may be applied in between the primary layers, such as polyurea/polyurethane layers after the aliphatic polyurea layer or one or more additional structural foam layers after the primary structural foam layer.