Viscoelastic Plastic Interlayer for Automotive Glazing Acoustic Damping
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Solution Overview
Problem
Existing laminated glazings with vibroacoustic damping properties face challenges in achieving improved acoustic insulation while maintaining satisfactory stiffness, transparency, and lightness, especially at the coincidence frequency, and must meet stringent safety and mechanical resistance requirements for automotive applications.
Innovation Solution
A viscoelastic plastic interlayer comprising two outer layers of standard polyvinyl butyral (PVB) and an inner layer with a high loss factor tan δ, combined with barrier layers of viscoelastic plastic material like polyester, is used between glass sheets, along with a liquid coating process to integrate a colloid-based inner layer for enhanced acoustic insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a tri-layer acoustic interlayer of PVB is used, then acoustic insulation is improved, but stiffness and weight are increased
Solution Approach 1:
The interlayer is divided into multiple functional layers: outer PVB layers (0.2-0.8 mm each) for structural integrity and stiffness, a thin inner viscoelastic layer (0.01-0.1 mm) for acoustic damping, and barrier layers (1-10 µm) to prevent chemical diffusion. This segmentation allows each layer to perform its specific function optimally while keeping the total weight low.
Solution Approach 2:
The invention uses a composite interlayer structure combining different materials: PVB (polyvinyl butyral) for adhesion and structural properties, viscoelastic polymers (such as polyester/PET) for acoustic damping with high loss factor (tan δ ≥ 1.6), and thin barrier layers. This composite approach achieves superior acoustic insulation without proportionally increasing weight.
2Object-affected harmful factors
If inner layer thickness is increased to improve acoustic damping, then acoustic insulation improves, but transparency and fineness deteriorate
Solution Approach 1:
The viscoelastic inner layer is applied locally as a thin coating (0.01-0.1 mm) on the barrier layers rather than using a thick uniform layer throughout. This localized application provides sufficient acoustic damping (tan δ ≥ 1.6) while maintaining the overall transparency and visual quality of the glazing.
Solution Approach 2:
The invention changes the thickness parameter of the viscoelastic layer to a very thin range (0.01-0.1 mm, i.e., 10-100 µm) and optimizes the loss factor parameter (tan δ ≥ 1.6) to achieve high acoustic damping performance in a thin layer, thereby maintaining transparency and fineness.
3Object-affected harmful factors
If viscoelastic polymer is used for acoustic damping, then acoustic insulation improves, but mechanical resistance and safety may be compromised
Solution Approach 1:
The interlayer is segmented into outer PVB layers (0.2-0.8 mm each) that provide mechanical strength and safety, and a thin inner viscoelastic layer (0.01-0.1 mm) for acoustic damping. The barrier layers (1-10 µm) separate these functional zones and prevent chemical diffusion, ensuring that the structural integrity is maintained while achieving acoustic performance.
Solution Approach 2:
The composite structure combines PVB (providing adhesion, stiffness, and mechanical resistance), viscoelastic polymer (providing acoustic damping with tan δ ≥ 1.6), and barrier layers. This composite approach ensures that mechanical strength requirements are met by the PVB outer layers while the thin viscoelastic inner layer provides acoustic insulation without compromising safety.
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 interlayer provides significant improvement in both airborne and structure-borne acoustic insulation within the 2000 Hz to 8000 Hz frequency range, while maintaining sufficient stiffness and transparency, and meets safety and mechanical resistance standards, as demonstrated by increased acoustic damping performance and reduced weight.
Implementation Method 1
an inner layer arranged between the two outer layers, said inner layer having a loss factor tan δ greater than or equal to 1.6 at 20° C. and for a frequency range of between 2 kHz and 8 kHz
Implementation Method 2
a first and a second barrier layer arranged respectively between said outer layers and the inner layer and composed of a viscoelastic plastic material, preferably polyester, in particular polyethylene terephthalate (PET)
Implementation Method 3
a liquid coating process to integrate a colloid-based inner layer
Data Source
AI summary
A viscoelastic plastic interlayer intended to be arranged between two glass sheets of a glazing in order to provide it with vibroacoustic damping properties, includes two outer layers of thermoplastic adhesive, an inner layer arranged between the two outer layers, the inner layer having a loss factor tan δ greater than or equal to 1.6 at 20° C. and for a frequency range of between 2 kHz and 8 kHz, and first and second barrier layers arranged respectively between the outer layers and the inner layer 3, and composed of a viscoelastic plastic material.