Two-Component Aerosol Can With Throttle Element
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Solution Overview
Problem
Two-component aerosol cans for sealing and assembly foams face challenges in achieving precise mixing ratios of prepolymer and curing agent, leading to isocyanate excess issues and foam contraction, which affect the quality and durability of the seal.
Innovation Solution
Incorporating a throttle element in the second valve channel to control the dispensing rate of the curing component, ensuring an isocyanate excess of more than 3 wt% in the mixture, and using a static mixer in the spray tube for homogeneous mixing, while maintaining identical valve designs for cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If separate valves are used for prepolymer and curing component, then simultaneous actuation and external mixing is achieved, but valve complexity increases and manufacturing cost rises
Solution Approach 1:
The patent combines two separate valve actuation mechanisms into a single spray head assembly. When the user presses the spray head, a common actuating force simultaneously opens both the first valve device for prepolymer and the second valve device for curing component, eliminating the need for separate actuation mechanisms while maintaining synchronized discharge.
Solution Approach 2:
The spray head is designed to serve multiple functions: it acts as the actuating mechanism for both valves, the mixing chamber for combining components, and the dispensing nozzle. This multi-functional design reduces overall system complexity while achieving simultaneous control of both components.
2Stability of the object's composition
If curing component dispensing rate is increased to match prepolymer, then complete mixing is achieved, but isocyanate excess is lost and foam contraction occurs
Solution Approach 1:
The patent applies different dispensing rates to different components based on their specific requirements. The throttle element creates a localized flow restriction specifically for the curing component channel, allowing the prepolymer to flow at a higher rate while the curing component flows at a controlled, lower rate, thereby maintaining the necessary isocyanate excess in the mixture.
Solution Approach 2:
The patent changes the flow rate parameter for the curing component by introducing a throttle element with a smaller cross-sectional area. This parameter modification ensures that the curing component dispenses at a controlled rate that maintains the optimal isocyanate excess ratio, preventing foam contraction while achieving sufficient mixing.
3Productivity
If throttle element with smaller cross-section is used for curing component, then dispensing rate is controlled, but valve design asymmetry increases manufacturing complexity
Solution Approach 1:
The asymmetry is localized only to the throttle element cross-sectional area within the valve bodies, not to the overall valve design. The valve mechanisms themselves remain symmetric and identical, with only the internal flow passage dimensions differing to control the dispensing rate of the curing component.
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 allows for precise control of the isocyanate excess, preventing foam contraction and ensuring a watertight seal with pressure resistance of over 1.5 bar, suitable for applications like pipe closures and joint sealing, with the foam maintaining airtight and watertight properties for over 120 hours.
Implementation Method 1
The pressurized can holds not only the prepolymer but also propellant gas, which serves first to dispense the prepolymer from the pressurized can
Implementation Method 2
using a static mixer in the spray tube for homogeneous mixing
Implementation Method 3
The sealing and assembly foams here are formed from a polyisocyanate-based prepolymer component and from a curing component, leading to the crosslinking of the polyisocyanate groups of the prepolymer component
Implementation Method 4
In addition there are customary adjuvants, such as flame retardants, foam stabilizers, and catalysts
Data Source
AI summary
A two-component aerosol can for dispensing sealing and assembly foams based on isocyanates, having an outer pressure container which holds a prepolymer component and a propellant gas, the outer pressure container being in communication with a first valve device and with a first channel; an inner container which holds a curing component and a propellant gas, the inner container being in communication with a second valve device and with a second channel; and a spray head which comprises a device for simultaneously actuating the first and second valve devices; and a spray tube into which the first and second channels jointly open.