Polyamide Composition for Low-Temperature Battery Overmolding

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Solution Overview

Problem

Conventional polyamides used in overmolding processes for batteries, particularly lithium-polymer batteries, require high temperatures and pressures, making them unsuitable for heat-sensitive elements and limiting recyclability, while also failing to provide adequate mechanical and thermal properties at lower temperatures.

Innovation Solution

A polyamide composition derived from the polycondensation of an acid component comprising fatty acid dimers, aliphatic diacids, chain limiters, aliphatic diamines, cycloaliphatic diamines, and polyetheramines, with a specific molar ratio, allowing for low-pressure and low-temperature injection molding with improved mechanical and thermal properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional polyamides are used for overmolding batteries, then mechanical strength and thermal stability are achieved, but high temperatures and pressures are required which damages heat-sensitive elements and reduces recyclability

Engineering Contradiction:
Improvemechanical strength and thermal stabilityVSAvoidhigh temperature and pressure damage to heat-sensitive elements
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the chemical composition parameters of the polyamide by incorporating specific ratios of fatty acid dimers (20-50 mol%), aliphatic diacids (30-70 mol%), and diamines (10-60 mol%). This compositional parameter change enables the polyamide to achieve adequate mechanical properties at lower processing temperatures (150-250°C) and pressures, thereby reducing thermal damage to heat-sensitive battery elements while maintaining reliability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polyamide material combining multiple components: fatty acid dimers providing thermal stability, aliphatic diacids contributing to mechanical strength, and diamines enhancing processability. This composite approach allows the material to achieve a balance of mechanical properties and thermal resistance at lower processing conditions, protecting heat-sensitive elements during overmolding

Inventive Principle:
Principle #40Composite materials

2Strength

If high temperature injection molding is used for battery casings, then mechanical properties are achieved, but heat-sensitive battery elements are damaged and recycling becomes difficult

Engineering Contradiction:
Improvemechanical properties of battery casingVSAvoidrecyclability and heat sensitivity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the processing temperature parameter from conventional high temperatures (>200°C) to lower temperatures (150-250°C) by modifying the polyamide composition. The specific formulation with fatty acid dimers and aliphatic diacids enables the material to achieve adequate mechanical strength at these reduced temperatures, facilitating easier manufacturing and recycling while protecting heat-sensitive battery elements

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If polyamide composition is modified for low-temperature processing, then heat-sensitive elements are protected, but mechanical and thermal properties may be compromised

Engineering Contradiction:
Improveprotection of heat-sensitive elementsVSAvoidmechanical and thermal properties
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent develops a composite polyamide system where fatty acid dimers (20-50 mol%) provide thermal stability, aliphatic diacids (30-70 mol%) contribute to mechanical strength, and diamines (10-60 mol%) enhance processability. This carefully balanced composite formulation ensures that even at lower processing temperatures, the material achieves adequate mechanical and thermal properties while protecting heat-sensitive elements

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the compositional parameters of the polyamide to achieve a critical balance point where low-temperature processing is possible without sacrificing mechanical integrity. The specific ranges of fatty acid dimer content, diacid content, and diamine content are tuned to ensure sufficient cross-linking density and molecular weight for reliable mechanical properties at reduced temperatures

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

Enables the production of battery casings with satisfactory mechanical and thermal properties, including impact strength at high temperature gradients, and facilitates easy recycling, while ensuring strong adhesion to various substrates at lower temperatures.

Implementation Method 1

a polyamide which is the product of the polycondensation of an acid component and of an amine component

Methodology Applied
Scientific EffectPolycondensation: Chemical Bonding

Data Source

PatentUS20230365752A1Polyamide composition
Publication Date: 2023.11.16 BOSTIK SA(FR)

AI summary

The present invention relates to a polyamide, to a composition comprising same, and to the use thereof, and also to a molded article deriving therefrom and to a process for producing same. The polyamide is particularly suitable as hot-melt adhesive for the low-pressure and low-temperature overmolding of a heat-sensitive battery, for example a lithium-polymer battery.