Filled Polyester Composition for Lightweight Vehicle Noise Damping
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Solution Overview
Problem
Existing sound dampening materials for vehicles face challenges in achieving effective sound attenuation at lower frequencies while minimizing weight increase and maintaining structural integrity, and there is a need for cost-effective solutions to meet future vehicle noise reduction regulations.
Innovation Solution
A polyester composition comprising a combination of first and second poly(alkylene terephthalate) polymers with reinforcing and inorganic fillers, including glass fibers and high specific gravity materials, which can be molded into articles with enhanced sound transmission loss without significant mass increase, allowing for laminates with improved sound damping characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If sound-absorbing materials are added to reduce vehicle noise, then sound transmission loss is improved, but vehicle weight increases
Solution Approach 1:
The patent uses a composite material system consisting of polyester resin combined with glass fibers (5-60 wt%) and barium sulfate (5-60 wt%). This composite structure achieves superior sound transmission loss (36-45 dB at 1250 Hz) while maintaining relatively low density. The glass fibers provide structural reinforcement and the barium sulfate contributes to acoustic attenuation through its high specific gravity (4.5 g/cm³), creating an effective sound-dampening composite that does not excessively increase vehicle weight.
Solution Approach 2:
The patent optimizes specific physical parameters of the sound dampening material, including the weight ratios of glass fibers (5-60 wt%) and barium sulfate (5-60 wt%), the polyester resin molecular weight (10,000-100,000 g/mol), and the material thickness (3.2 mm). By carefully controlling these parameters, the material achieves maximum sound transmission loss (36-45 dB at 1250 Hz) while minimizing weight increase, directly addressing the contradiction between acoustic performance and vehicle weight.
2Object-affected harmful factors
If sound dampening materials are incorporated to meet noise regulations, then sound attenuation is improved, but manufacturing cost increases
Solution Approach 1:
The patent specifies optimized parameter ranges to balance performance and cost: glass fibers (5-60 wt%), barium sulfate (5-60 wt%), polyester resin with molecular weight 10,000-100,000 g/mol, and material thickness of 3.2 mm. These parameter optimizations enable effective sound attenuation (36-45 dB at 1250 Hz) while controlling material costs and maintaining ease of manufacturing through standard molding processes.
Solution Approach 2:
The patent utilizes the porous and fibrous structure of glass fibers within the polyester matrix to achieve sound dampening. The glass fiber network creates tortuous paths for sound wave propagation, increasing acoustic attenuation effectiveness. This structural approach provides cost-effective sound control compared to dense solid materials, as glass fibers are relatively inexpensive and can be processed using standard composite manufacturing techniques.
3Object-affected harmful factors
If high mass per unit area materials are used to increase sound transmission loss, then sound attenuation is improved, but weight increase becomes excessive
Solution Approach 1:
The patent employs a multi-phase composite material where polyester resin serves as the continuous matrix, glass fibers (5-60 wt%) provide structural framework and acoustic scattering, and barium sulfate (5-60 wt%) with high specific gravity (4.5 g/cm³) contributes to mass loading effect for sound attenuation. This composite architecture achieves high sound transmission loss (36-45 dB at 1250 Hz) per unit mass, avoiding the need for excessive material thickness or mass that would otherwise be required with single-phase materials.
Solution Approach 2:
The patent applies local quality enhancement by incorporating barium sulfate particles specifically within the polyester-glass fiber composite matrix. The barium sulfate's high specific gravity (4.5 g/cm³) is strategically utilized in the sound-dampening regions to increase acoustic impedance and improve sound transmission loss locally, rather than uniformly increasing the entire material's mass. This localized approach optimizes sound attenuation efficiency while controlling overall weight.
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 achieves sound transmission loss of greater than 30 decibels at 1250 Hz with reduced weight, offering improved sound damping and structural strength, while incorporating post-consumer recycled materials and allowing for efficient manufacturing processes.
Implementation Method 1
an inorganic filler having a specific gravity of greater than 3.0 grams per cubic centimeter... wherein a molded article comprising the polyester composition has a sound transmission loss of greater than 30 decibels
Data Source
AI summary
A polyester composition comprising, based on the total weight of the polyester composition, a first polyester and a second polyester, wherein a weight ratio of the first polyester to the second polyester is 80:20 to 20:80, preferably 60:40 to 40:60; 5 to 60 weight percent (wt%), preferably 5 to 50 wt% of a reinforcing filler; and 5 to 60 wt%, preferably 10 to 50 wt%, more preferably 20 to 50 wt% of an inorganic filler having a specific gravity of greater than 3 grams per cubic centimeter, as determined in accordance with ASTM D792, wherein a molded article comprising the polyester composition has a sound transmission loss of greater than 30 dB, preferably 35 to 50 dB, more preferably 36 to 45 dB, as determined at 1,250 Hz according to ASTM E1050 using a molded disc with a diameter of 100 mm and a thickness of 3.2 mm.