Occluded Polymer Particle Dispersion for Water-Resistant LASD Coatings
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Solution Overview
Problem
Existing liquid applied sound damping (LASD) coatings lack sufficient water resistance, limiting their application in areas like vehicle wheel wells and requiring improvements for better damping performance and appearance.
Innovation Solution
An aqueous dispersion of multiphase polymer particles with specific Tg ranges and molecular weights, incorporating high methyl methacrylate second polymer particles occluded within first polymer particles, enhances water resistance and damping performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LASD coatings are used, then damping performance and ease of application are improved, but water resistance is insufficient
Solution Approach 1:
The patent employs a multiphase polymer particle system comprising soft polymer particles (Tg < 30°C) and hard polymer particles (Tg 90-110°C) with specific composition ratios. This composite structure provides both the damping performance needed for NVH management and the water resistance required for harsh environments like wheel wells, resolving the contradiction between conventional LASD coating limitations and the need for enhanced water resistance.
Solution Approach 2:
The patent specifies precise parameter ranges including polymer particle Tg values, molecular weight (9,000-25,000 g/mole), and composition percentages (80-95 wt% soft polymer, 5-20 wt% hard polymer). By optimizing these parameters, the coating achieves both excellent damping performance and superior water resistance, enabling expansion into new application areas while maintaining reliability in existing applications.
2Reliability
If bitumen pads are used, then cost is reduced, but damping performance and water resistance are poor
Solution Approach 1:
The patent defines specific parameter ranges for polymer molecular weight (9,000-25,000 g/mole), Tg values, and composition ratios that optimize damping performance while maintaining water resistance. These parameter specifications enable the coating to outperform bitumen pads in both damping and water resistance, while the aqueous dispersion formulation allows for efficient robotic spray application, reducing application complexity.
Solution Approach 2:
The patent replaces the manual application method required for bitumen pads with a robotic spray application system compatible with aqueous dispersions. This substitution maintains ease of manufacture through automated application while achieving superior damping performance and water resistance that bitumen pads cannot provide.
3Reliability
If polymer particles with specific Tg ranges are used, then water resistance is improved, but formulation complexity increases
Solution Approach 1:
The patent specifies precise parameter ranges (Tg < 30°C for soft polymer, 90-110°C for hard polymer, molecular weight 9,000-25,000 g/mole) that simultaneously achieve water resistance and damping performance. While these parameters increase formulation complexity, the systematic approach to selecting polymers within these ranges provides reliable water resistance and excellent appearance, justifying the increased formulation precision.
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 composition forms a blister-free, water-resistant coating with excellent appearance and high damping performance, suitable for various applications including vehicle wheel wells.
Implementation Method 1
the second polymer particles are phase separated from and occluded within the first polymer particles
Implementation Method 2
first polymer particles having a Tg of less than 30° C., and from greater than 5 to less than 20 weight percent of second polymer particles having a Tg in the range of from 90° C. to 110° C.
Data Source
AI summary
The present invention relates to a composition comprising an aqueous dispersion of multiphase polymer particles comprising first polymer particles having a Tg of less than 30° C. and second polymer particles having a Tg in the range of from 100° C. to 110° C., wherein the second polymer particles are phase separated from and occluded within the first polymer particles; wherein the number average molecular weight (Mn) of the multiphase polymer particles is in the range of from 9,000 to 25,000 g/mole; and wherein the second polymer particles comprise at least 95 weight percent methyl methacrylate. The composition of the present invention is useful in a formulation that can be used to prepare a water-resistant blister free LASD coating with little or no surface defects.