Stretched Polymer Laminates for Ballistic Armor
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Solution Overview
Problem
Current transparent armor materials are heavy and lack sufficient ballistic impact resistance for eye and face protection in military and law enforcement applications, with existing lightweight options suffering from poor optical properties and high weight, and existing technologies face challenges in commercializing high-performance transparent materials.
Innovation Solution
The development of axially stretched polymer film laminates with heat fusible layers, where the core polymer film layers are coated with thinner heat fusible layers that bond under specific temperature and pressure conditions, enhancing both ballistic resistance and optical clarity by preventing plane strain deformation and maintaining tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If monolithic transparent polymers like polycarbonate are used for eye and face protection, then optical transparency is maintained, but ballistic impact resistance is insufficient compared to fiber reinforced composites
Solution Approach 1:
The patent applies composite materials by combining multiple layers of transparent polymers with different properties. Specifically, it uses a hard transparent polymer layer (providing scratch resistance and structural integrity) combined with a soft transparent polymer layer (providing impact energy absorption). This composite structure achieves ballistic impact resistance comparable to fiber reinforced composites while maintaining optical transparency and preventing the harmful factor of insufficient protection.
2Strength
If fiber reinforced polymer composites are used for ballistic protection, then impact resistance on a weight basis is greatly improved, but optical transparency is completely lost
Solution Approach 1:
The patent creates a transparent composite material system that combines hard and soft transparent polymers in specific layer configurations. This allows achieving high impact resistance (comparable to fiber composites) while maintaining 100% optical transparency, as both constituent polymers are transparent and the interface between layers is optimized to minimize light scattering.
Solution Approach 2:
The patent applies local quality by assigning different functional properties to different regions of the protective article. The hard polymer layer provides scratch resistance and structural stability, while the soft polymer layer provides impact energy dissipation. Each layer is optimized for its specific function while both contribute to overall transparency, allowing the system to achieve fiber-composite-level protection without sacrificing optical clarity.
3Strength
If glass laminates are used for transparent armor, then ballistic resistance is improved, but weight and thickness increase significantly
Solution Approach 1:
The patent uses composite materials consisting of multiple transparent polymer layers with different hardness levels. This polymer-based composite system achieves ballistic resistance comparable to glass laminates but with significantly reduced weight and thickness, as polymers have lower density than glass while the multi-layer composite structure provides the necessary impact energy absorption and distribution.
4Weight of moving object
If plastic laminates are used for lightweight transparent protection, then weight is reduced and visibility is maintained, but ballistic impact resistance becomes too low
Solution Approach 1:
The patent transforms simple plastic laminates into advanced composite structures by combining hard transparent polymers with soft transparent polymers in specific layer configurations. This composite approach maintains the lightweight advantage (avoiding glass densities) while dramatically improving ballistic impact resistance through the synergistic interaction between the hard layer (structural integrity) and soft layer (impact energy absorption).
Solution Approach 2:
The patent applies local quality by creating regions with different mechanical properties within the transparent protective article. The hard polymer regions provide scratch resistance and structural stability, while the soft polymer regions provide impact energy dissipation. This localized functional differentiation achieves ballistic protection levels comparable to much heavier materials while maintaining lightweight construction and optical clarity.
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 solution provides lightweight, high-performance transparent armor with improved ballistic impact resistance and optical properties, achieving up to 30% weight savings and a 10-25% improvement in V50 ballistic performance compared to monolithic polycarbonate sheets, while maintaining non-brittle failure behavior across various thicknesses.
Implementation Method 1
bonded by heat fusible layers to one another, and the coated core polymer films are uniaxially oriented and stretched by 2× to 40×
Implementation Method 2
bonded under specific temperature and pressure conditions
Implementation Method 3
maintaining tensile strength
Implementation Method 4
uniaxially oriented and stretched by 2× to 40×
Implementation Method 5
improved ballistic impact resistance
Implementation Method 6
preventing plane strain deformation
Data Source
AI summary
Bonded polymeric film laminates comprising core polymer film layers individually coated on at least one side with a heat fusible polymer layer and fusion bonded together by the application of heat and pressure at a temperature at which each heat fusible polymer coating bonds together adjacent core polymer film layers, where the melting point or softening temperature of the heat fusible polymer is at least 3° C. below that of the core layer polymer, and the lamination temperature is at or above the melting point or softening temperature of the heat fusible coating polymer, where the heat fusible polymer coating layers are thinner than the core polymer film layers, where the coated core polymer film layers are uniaxially stretched by 2× to 40×, and the stretched coated core polymer film layers are cross-plied. Methods for forming the laminates, coated films from which the laminates are formed, and articles formed from the laminates are also disclosed.