Polymer Blend for Metal-Polymer Composites

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Solution Overview

Problem

Current polymer mixtures used in metal-polymer composites face issues with high melting points, incompatibility with bonding equipment, and poor adhesion due to high processing temperatures and uneven distribution of components, particularly in cataphoresis processes used in the automotive industry.

Innovation Solution

A biphasic polymer mixture comprising a polyamide with a melting point of up to 210°C and a modified polyolefin with carboxylic functions, exhibiting threshold stress fluid behavior, which resists creep and ensures adhesion and rigidity, along with the addition of fillers to enhance properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a polymeric mixture with high melting point (220°C) is used to ensure adhesion and rigidity, then the polymer can withstand processing temperatures, but it becomes incompatible with bonding assembly equipment that cannot reach temperatures above 220°C

Engineering Contradiction:

Improvemelting pointVSAvoidcompatibility with bonding equipment

Core Design Contradiction:

TemperatureVSAdaptability or versatility

Solution Approach 1:

The patent changes the thermal parameters of the polymer mixture by selecting specific polyamide types (PA6, PA66, PA12) with lower melting points (below 220°C) and adjusting their proportions in the mixture. This allows the composite to be processed with available bonding equipment while maintaining the required adhesion and rigidity properties through optimized formulation rather than relying on high temperature alone.

Inventive Principle:

Principle #35Parameter changes

2Strength

If the polymer becomes too fluid at high processing temperatures to allow melting and spreading, then adhesion to metal can be achieved, but the metal sheets slip and the composite is destroyed during cataphoresis

Engineering Contradiction:

Improveadhesion to metalVSAvoidresistance to creep during cataphoresis

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent uses a composite polymer mixture combining polyamide with modified polyethylene and SMA copolymer. This composite formulation creates a synergistic effect where the polyamide provides adhesion to metal, while the modified polyethylene and SMA copolymer contribute to creep resistance. The combination allows the polymer to maintain sufficient viscosity at processing temperatures to prevent metal sheet slippage during cataphoresis while still achieving adequate adhesion.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The modified polyethylene acts as an intermediary component that modifies the rheological behavior of the polymer mixture. It provides a balance between fluidity at processing temperature (enabling spreading and adhesion) and viscosity at service temperature (preventing creep during cataphoresis). The carboxylic functions in the modified polyethylene also enhance interfacial adhesion to the metal substrate.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If styrene-maleic anhydride (SMA) copolymer is added to improve adhesion and rheological properties, then the polymer mixture can achieve satisfactory performance, but homogeneous distribution of SMA copolymer becomes difficult to ensure

Engineering Contradiction:

ImproveadhesionVSAvoidhomogeneity of distribution

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The modified polyethylene with carboxylic functions serves as a compatibilizer and intermediary between the polyamide and SMA copolymer phases. It facilitates homogeneous distribution of the SMA copolymer throughout the polymer mixture by reducing phase separation and improving interfacial compatibility, thereby achieving uniform morphology and consistent adhesion properties without difficult processing.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 polymer mixture effectively withstands cataphoresis temperatures, maintains adhesion, and provides the necessary mechanical properties for metal-polymer composites, ensuring resistance to creep and thermal stress while ensuring compatibility and homogeneity.

Implementation Method 1

exhibiting threshold stress fluid behavior, which resists creep

Methodology Applied

Scientific EffectThreshold stress fluid behavior: Bingham Plastic

Implementation Method 2

The polymers used for these composites must meet many requirements, including adhesion to metal

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 3

the polymer mixture effectively withstands cataphoresis temperatures, maintains adhesion, and provides the necessary mechanical properties for metal-polymer composites, ensuring resistance to creep and thermal stress

Methodology Applied

Scientific EffectThermal stress resistance: Thermal Shock

Data Source

PatentEP2649107B1Blend of polymers having yield stress and use thereof for the manufacture of metal-polymer composites

Publication Date: 2017.02.08 ARCELORMITTAL SA

AI summary

The invention relates to a two-phase polymer blend, comprising: (a) a polyamide having a melting point at most equal to 210°C, (b) a polyolefin modified by grafting of carboxyl functions, the rheological behaviour of which in the melt state is characterized by the existence of a yield stress, and also to a process for the preparation thereof. The invention furthermore relates to the use of this polymer blend for the manufacture of composite structures and facings and also the resulting composite structures and facings.