Viscoelastic Plastisol Coating for Vehicle Underbody NVH Reduction
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Solution Overview
Problem
Current vibration damping materials for vehicle substrates, such as plasticized PVC coatings, fail to provide adequate noise reduction across a range of temperatures and frequencies, leading to insufficient noise, vibration, and harshness (NVH) mitigation, especially in low-frequency ranges, and often come with drawbacks like weight addition, high curing temperatures, and prolonged curing times.
Innovation Solution
A plastisol formulation comprising a polymeric component, a plasticizer, and a rosin ester resin, with specific plasticizers like di-2-ethylhexyl terephthalate and tri-2-ethylhexyl trimellitate, and a rosin ester resin with a softening point between 60° C to 96° C, applied to vehicle substrates to enhance vibration damping performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plasticized PVC coatings are used for vibration damping, then ease of application and economy are improved, but vibration damping performance across temperature and frequency ranges deteriorates
Solution Approach 1:
The patent combines plasticized PVC with viscoelastic polymers (such as polyisobutylene, polybutadiene, or styrene-butadiene rubber) to create a composite coating formulation. This composite approach leverages the ease of application and corrosion protection of PVC while incorporating the superior vibration damping and temperature-dependent performance characteristics of viscoelastic materials, thereby resolving the contradiction between manufacturing ease and damping performance reliability
Solution Approach 2:
The patent modifies the coating formulation by incorporating plasticizers and viscoelastic polymers in specific proportions, and by controlling cure conditions (temperature and time parameters), to achieve optimal damping performance across different temperature ranges. The formulation parameters are adjusted to ensure the coating maintains appropriate tan δ values at various temperatures while remaining easy to apply
2Reliability
If asphaltic pads are used for noise suppression, then vibration damping is improved, but weight increases and manual application is required
Solution Approach 1:
The patent employs a liquid-applied coating formulation that forms a thin, flexible film on the substrate after curing. This thin-film approach provides effective vibration damping through the viscoelastic properties of the cured coating while minimizing added weight compared to traditional thick asphaltic pads, and enables automated application processes
Solution Approach 2:
The patent replaces the mechanical/adhesive-based damping mechanism of thick asphaltic pads with a chemically-cured viscoelastic coating system. The damping effect is achieved through the molecular viscoelastic behavior of the cured polymer network rather than through the mechanical compliance of thick adhesive layers, reducing weight while maintaining damping effectiveness
3Reliability
If materials requiring high temperature and long curing times are used, then vibration damping performance is improved, but productivity decreases and energy usage increases
Solution Approach 1:
The patent formulates the coating with catalysts and curing agents that enable the viscoelastic polymer network to develop adequate damping performance at lower temperatures and shorter times. By adjusting the chemical composition and curing parameters, the patent achieves effective damping (tan δ > 0.2) with reduced energy input and faster cycle times, resolving the contradiction between performance reliability and production productivity
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 plastisol formulation significantly improves vibration damping across the desired temperature and frequency range, achieving higher tan δ values, thus effectively reducing NVH, while maintaining ease of application and reducing material weight.
Implementation Method 1
Polymeric materials can damp, or reduce oscillations of, a substrate by dissipating the oscillation energy with their viscoelastic behavior
Implementation Method 2
The softening point of the rosin ester resin ranges from 60° C. to 96° C.
Implementation Method 3
dissipating the oscillation energy with their viscoelastic behavior
Data Source
AI summary
Disclosed is a method for improving vibration damping of a substrate, such as the underbody of an automobile. The method comprises applying a plastisol which comprises a polymeric component, a general purpose plasticizer and a rosin ester resin. The fused plastisol has improved damping behavior as determined using Dynamic Mechanical Thermal Analysis.