Thermoplastic Composite Helmet Shell Overmoulding Adhesion

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Solution Overview

Problem

Existing body protections face challenges in achieving a lightweight, cost-effective, and structurally integrated combination of a structural shell with an expanded polystyrene layer, particularly in helmets, where adhesion is limited, leading to potential detachment and increased weight or cost.

Innovation Solution

A manufacturing method involving a thermoplastic structural shell with embedded reinforcing fibers and a closely attached expanded polystyrene layer, achieved through over-moulding at controlled temperatures, ensuring adhesion without adhesives and enhancing structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a non-structural shell made of polycarbonate is used with an expanded polystyrene layer, then abrasion protection is improved, but adhesion between the shell and polystyrene layer deteriorates leading to detachment over time

Engineering Contradiction:

Improveabrasion resistanceVSAvoidadhesion stability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent changes the material parameter of the shell from polycarbonate to thermoplastic material with specific melting temperature range (160-200°C), which allows the shell to be softened during overmoulding process to achieve strong adhesion with the expanded polystyrene layer while maintaining abrasion resistance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite material consisting of thermoplastic matrix combined with reinforcing fibres (glass, carbon, or aramid) to create a shell that simultaneously achieves abrasion resistance, structural strength, and thermal properties suitable for overmoulding adhesion

Inventive Principle:

Principle #40Composite materials

2Strength

If a structural shell with high thickness is used, then impact protection is improved, but weight increases making it uncomfortable for prolonged wear

Engineering Contradiction:

Improveimpact protectionVSAvoidhelmet weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent employs composite materials with reinforcing fibres (glass, carbon, or aramid) embedded in thermoplastic matrix to achieve high impact protection with reduced thickness, thereby reducing weight while maintaining structural strength

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent implements local reinforcement by incorporating fibres specifically in the structural shell where impact protection is needed, while keeping the overall shell thickness minimized for weight reduction

Inventive Principle:

Principle #3Local quality

3Weight of moving object

If composite structural shells with thermosetting matrix are used, then weight is reduced, but adhesion with expanded polystyrene layer deteriorates due to high melting temperature

Engineering Contradiction:

Improveshell weightVSAvoidadhesion strength

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent changes the matrix material parameter from thermosetting to thermoplastic with melting temperature between 160-200°C, enabling the shell to be softened during overmoulding to achieve strong adhesion while maintaining reduced weight through composite structure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent adopts the successful adhesion mechanism of thermoplastic materials (that can be softened for overmoulding) and applies it to the composite shell structure, copying the thermal processing approach from conventional thermoplastics to fibre-reinforced composite materials

Inventive Principle:

Principle #26Copying

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 method results in a helmet with improved strength, reduced weight, and lower manufacturing costs by integrating a thermoplastic composite shell with a closely adhered expanded polystyrene layer, enhancing performance and reducing thickness.

Implementation Method 1

a manufacturing step, by means of over-moulding, of said expanded polystyrene layer on the intrados of the structural shell, producing its adhesion by close contact to the structural shell

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

an expanded polystyrene layer which absorbs the energy of the large impacts to protect the head contained in the helmet

Methodology Applied

Scientific EffectEnergy absorption: Deformation

Data Source

PatentEP4056062B1Method for producing a body protection item and resulting body protection item

Publication Date: 2026.04.01 MAT PROD & TECH S L U

Figure 1
Figure 2

AI summary

Manufacturing method of a body protection and resulting body protection, wherein the method comprises producing a structural shell (10) with a maximum thickness of 5 mm, made of thermoplastic material, and defining a concave interior (11) and a convex exterior (12); over-moulding an expanded polystyrene layer (20) overlapping the concave interior (11) of the structural shell (10), producing its adhesion by close contact to the structural shell (10); and wherein the structural shell (10) is produced by means of the distributed placement, in a mould, of a mixture of thermoplastic material and of reinforcing fibres stable at temperatures equal to or lower than the melting temperature of the thermoplastic material, the closure and heating of the mould causing the melting of the thermoplastic material without damaging the reinforcing fibres, and the subsequent cooling of the mould, hardening the thermoplastic material with the reinforcing fibres embedded therein.