Polyurethane Fiber Composite Battery Cover for Thin Thermal Insulation

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Solution Overview

Problem

Existing materials for battery pack covers, such as stamped metal sheets and polypropylene or polyamide injection molding, are heavy, costly, and difficult to produce large components efficiently, lacking flame resistance and thermal insulation, while polyurethane foam is too thick for thinner applications.

Innovation Solution

A polyurethane composite comprising 35 to 75 wt% reinforced fiber and 25 to 65 wt% polyurethane foam, produced through a spray transfer molding process, with a two-component reactive system including isocyanate and polyol components, and a laminated product with thermal insulation layers for improved mechanical strength and flame resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If stamped metal sheet is used as battery pack cover, then mechanical strength and flame resistance are improved, but weight increases

Engineering Contradiction:

Improvemechanical strengthVSAvoidweight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent uses a composite material consisting of polyurethane foam combined with continuous reinforced fibers (75-100 wt% of total fiber content). This composite structure provides both the mechanical strength needed for battery pack covers and significantly reduces weight compared to solid metal sheets, while maintaining flame resistance through the polyurethane foam's inherent fire-retardant properties.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If polypropylene or polyamide injection molding is used, then lightweight is achieved, but manufacturing complexity and tooling cost increase for large components

Engineering Contradiction:

ImproveweightVSAvoidmanufacturing complexity

Core Design Contradiction:

Weight of moving objectVSEase of manufacture

Solution Approach 1:

The patent replaces complex injection molding processes with a simpler spray transfer molding process. Instead of requiring high-pressure injection equipment and complex tooling for large components, the invention uses spray application of polyurethane foam combined with continuous fiber reinforcement, significantly reducing tooling costs and manufacturing complexity while maintaining lightweight properties.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If conventional polyurethane foam is used, then flame resistance is improved, but thickness increases

Engineering Contradiction:

Improveflame resistanceVSAvoidthickness

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent modifies the polyurethane foam parameters by incorporating continuous reinforced fibers at high content (75-100 wt% of total fiber), which allows the foam to achieve the required mechanical strength and flame resistance at reduced thickness. The continuous fiber reinforcement enables the use of thinner foam sections while maintaining structural integrity and fire-retardant properties.

Inventive Principle:

Principle #35Parameter changes

4Strength

If SMC process is used to produce polyurethane foam sheet, then mechanical strength is improved, but density and component thickness increase

Engineering Contradiction:

Improvemechanical strengthVSAvoiddensity

Core Design Contradiction:

StrengthVSWeight of stationary object

Solution Approach 1:

The patent applies local quality by using continuous fiber reinforcement specifically in the polyurethane foam structure, concentrating the reinforcement where needed for mechanical strength while maintaining the lightweight foam matrix. This localized fiber reinforcement approach achieves high strength-to-density ratio, avoiding the need for thick, dense components required by SMC processes.

Inventive Principle:

Principle #3Local quality

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 composite achieves lightweight, cost-effective production with excellent mechanical strength, flame resistance, and thermal insulation, suitable for battery pack covers.

Implementation Method 1

a two-component reactive system comprising an isocyanate component consisting of (a) at least one isocyanate or isocyanate prepolymer, and a polyol component consisting of (b) at least one polyol reactive toward isocyanate

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentUS20250277093A1Polyurethane composite, laminated product comprising the polyurethane composite and process for producing the same

Publication Date: 2025.09.04 BASF (CHINA) CO LTD

AI summary

Disclosed herein are a novel polyurethane (PU) composite, a process for producing the PU composite and a covering article containing the PU composite. The PU composite includes 35 to 75 wt % reinforced fiber and 25 to 65 wt % polyurethane foam, based on the total weight of the PU composite, where the reinforced fiber includes 75 to 100 wt % of the reinforced fiber in a continuous phase form and 0 to 25 wt % of the reinforced fiber in a discontinuous phase form, based on the total weight of reinforced fiber. Further disclosed are a laminated product including at least one thermal insulating layer and at least two polyurethane composites arranged on each side of the thermal insulating layer, a process for producing the laminated product and a covering article for battery system containing the laminated product.