Cellulose Ester Interlayer for Structural Laminates
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Solution Overview
Problem
Current interlayers, particularly in structural laminates and human machine interface devices, face challenges in providing sufficient structural support while maintaining optical clarity and impact resistance, with existing materials like PVB interlayers exhibiting deficiencies in processability and functionality, and the need for lighter weight and lower cost laminates that retain desired physical and optical properties.
Innovation Solution
A multilayer interlayer comprising a cellulose ester layer and a non-cellulose ester layer, such as poly(vinyl acetal) resin, ethylene vinyl acetate resin, or thermoplastic polyurethane resin, with a tie layer to achieve low birefringence and improved adhesion, allowing for the creation of laminates with enhanced structural support and optical clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PVB interlayers are used to provide structural support, then load bearing ability is improved, but processability and functionality deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the interlayer by using cellulose esters with specific degree of substitution (DS) values and molecular weights, along with controlled plasticizer content, to achieve optimal balance between structural strength and processability. This allows the interlayer to meet structural requirements while maintaining ease of manufacturing.
2Weight of stationary object
If glass thickness is reduced to achieve lighter weight laminates, then weight is reduced, but rigidity deteriorates
Solution Approach 1:
The patent employs composite interlayer structures combining cellulose ester layers with plasticizers, and potentially multiple layers with different properties, to create a material that provides enhanced rigidity. This composite approach allows the use of thinner glass while maintaining overall laminate rigidity through the superior mechanical properties of the composite interlayer.
3Ease of manufacture
If standard PVB interlayers are used, then manufacturing simplicity is maintained, but optical properties and structural performance deteriorate
Solution Approach 1:
The patent modifies the chemical parameters of the interlayer material by selecting cellulose esters with specific degree of substitution ranges (DS 2.0-3.0) and controlling plasticizer content (10-40 phr), which improves optical properties such as reducing birefringence while maintaining manufacturing feasibility through established lamination processes.
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 proposed solution enables the production of laminates with improved structural support, low birefringence, and impact resistance, suitable for use in structural applications and human machine interface devices, while reducing weight and cost, and maintaining excellent optical properties.
Implementation Method 1
A multilayer interlayer comprising a cellulose ester layer and a non-cellulose ester layer... with a tie layer to achieve low birefringence
Data Source
AI summary
An interlayer structure having a cellulose ester layer for use in bilayer 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 and HMI devices.