Cellulose Ester Multilayer Interlayers for Structural Laminates
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Solution Overview
Problem
Existing interlayers in structural laminates, such as those used in architectural glass applications, face challenges in providing sufficient structural support while maintaining optical clarity and avoiding processability deficiencies, particularly with commercially available PVB interlayers.
Innovation Solution
A multilayer interlayer comprising a cellulose ester layer treated with a boron-containing compound and a non-cellulose ester layer, such as poly(vinyl acetal) or ethylene vinyl acetate, which offers improved stiffness and adhesion, maintaining optical properties and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PVB interlayers are used to provide structural support, then stiffness and load bearing ability are improved, but optical clarity and adhesion properties deteriorate
Solution Approach 1:
The patent uses a composite interlayer structure combining cellulose acetate propionate (CAP) as the base layer with a boron-containing compound and thermoplastic polymer coating. This composite structure provides both structural support from the CAP layer and enhanced adhesion/stiffness from the boron-treated surface, while maintaining optical clarity through the transparent polymer coating.
Solution Approach 2:
The patent modifies the surface properties of the cellulose acetate propionate layer by treating it with a boron-containing compound. This parameter change increases the glass transition temperature and stiffness of the interlayer without compromising optical clarity, as the boron treatment is applied at the molecular level within the polymer matrix.
2Strength
If PVB interlayers are used to enhance stiffness, then load bearing ability is improved, but adhesion to substrates deteriorates
Solution Approach 1:
The patent introduces a thermoplastic polymer coating as an intermediary layer between the cellulose acetate propionate layer and the glass substrates. This intermediary layer contains adhesion promoters that enhance bonding to the substrates while the boron-containing compound in the CAP layer provides the necessary stiffness, thus resolving the adhesion-stiffness contradiction.
Solution Approach 2:
The multi-layer composite structure with CAP layer, boron-containing compound, and thermoplastic polymer coating provides both stiffness from the CAP layer and improved adhesion from the polymer coating, eliminating the need to choose between these properties.
3Illumination intensity
If glass thickness is reduced to maintain clarity, then optical properties are improved, but structural support capability deteriorates
Solution Approach 1:
The patent changes the parameters of the interlayer by treating cellulose acetate propionate with a boron-containing compound, which increases the glass transition temperature and stiffness. This allows the use of thinner glass panes while maintaining structural support capability, as the enhanced interlayer stiffness compensates for the reduced glass thickness.
Data Source
AI summary
An interlayer structure having a cellulose ester layer for use in structural laminates is described herein. The cellulose ester layer provides rigidity and support to multilayer interlayers comprising an array of different layers. Due to the diverse properties of the cellulose ester layers, the present interlayers can be useful in producing structural laminates having high stiffness and which possess good optical clarity for a variety of applications, including outdoor structural applications.