Ballistic Resistant Articles Using High Molecular Weight Polyethylene

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Solution Overview

Problem

Existing ballistic-resistant materials face challenges in achieving high ballistic performance while maintaining low areal weight and stability, as they often compromise on one or more of these properties.

Innovation Solution

A ballistic-resistant moulded article comprising a compressed stack of sheets with at least 20 wt.% polyethylene elongate bodies, specifically tapes or fibers with a weight average molecular weight of at least 100,000 g/mole and a narrow molecular weight distribution, and high uniplanar orientation parameters, which are stacked non-unidirectionally and compressed under pressure to enhance mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional ballistic-resistant materials are used, then adequate ballistic protection is achieved, but areal weight increases and stability decreases

Engineering Contradiction:

Improveballistic performanceVSAvoidareal weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent applies parameter changes by precisely controlling the molecular weight distribution of polyethylene elongate bodies (Mw/Mn ratio of at most 6) and their orientation parameters (200/110 uniplanar orientation parameter of at least 3). These parameter optimizations enable achieving high ballistic performance with reduced areal weight compared to conventional materials.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by creating a compressed stack of sheets containing polyethylene elongate bodies combined with other reinforcing elongate bodies. This composite structure allows optimization of ballistic performance while controlling areal weight through the specific composition and arrangement of different material components.

Inventive Principle:

Principle #40Composite materials

2Reliability

If conventional ballistic-resistant materials are used, then adequate ballistic protection is achieved, but material stability deteriorates

Engineering Contradiction:

Improveballistic performanceVSAvoidmaterial stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent improves material stability by controlling the molecular weight distribution parameter (Mw/Mn ratio of at most 6) and orientation parameters of the polyethylene elongate bodies. These parameter controls ensure consistent material properties and enhanced stability while maintaining ballistic performance.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If polyethylene elongate bodies with optimized molecular weight distribution and orientation are used, then ballistic performance and strength are improved, but manufacturing complexity increases

Engineering Contradiction:

Improveballistic performanceVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-orienting the polyethylene elongate bodies before compression, achieving the required 200/110 uniplanar orientation parameter of at least 3 through controlled stacking of sheets. This preliminary orientation step simplifies the overall manufacturing process compared to attempting to achieve orientation during compression.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent manages manufacturing complexity by specifying clear parameter ranges for molecular weight distribution (Mw/Mn ratio of at most 6) and orientation (200/110 uniplanar orientation parameter of at least 3). These defined parameters provide manufacturing guidance and quality control criteria, making the complex requirements more manageable.

Inventive Principle:

Principle #35Parameter changes

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 results in a material with improved ballistic performance, high tensile strength, energy absorption, and low areal weight, effectively addressing the limitations of existing materials by optimizing molecular weight distribution and orientation parameters.

Implementation Method 1

The solution results in a material with improved ballistic performance, high tensile strength, energy absorption

Methodology Applied

Scientific EffectEnergy absorption: Viscoelasticity

Implementation Method 2

compressing the stack under a pressure of at least 0.5 MPa

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentEP2313736B1Ballistic resistant articles comprising elongate bodies

Publication Date: 2019.01.23 TEIJIN ARAMID BV

AI summary

The invention pertains to a ballistic-resistant moulded article comprising a compressed stack of sheets comprising reinforcing elongate bodies, wherein at least some of the elongate bodies are polyethylene elongate bodies which have a weight average molecular weight of at least 100 000 gram/mole and a Mw/Mn ratio of at most 6. The polyethylene elongate bodies preferably have a weight average. molecular weight of at least 300 000 gram/mole, in particular at least 400 000 gram/mole, still more in particular at least 500 000 gram/mole. When polyethylene elongate bodies are tapes, they preferably have a 200/110 uniplanar orientation parameter of at least 3. Where the elongate bodies are fibres, they preferably have a 020 uniplanar orientation parameter of at most 55. A method for manufacturing the ballistic-resistant moulded article is also claimed.