Conversion-Coated Metal Plate Press-Formability Adhesiveness Trade-off

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Solution Overview

Problem

Conventional chemical conversion coated metal sheets face challenges in press-formability and adhesiveness, with high kinetic friction coefficients hindering press-molding and the addition of polyethylene wax improving press-formability but decreasing adhesiveness.

Innovation Solution

A chemical conversion coated metal sheet with a chemical conversion coating film containing a water-soluble resin, a lubricant with carbon-oxygen bonds, and colloidal silica, applied to a metal substrate, enhancing corrosion resistance, press-formability, and adhesiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If polyethylene wax is added to the chemical conversion coating film to improve press-formability, then press-formability is improved, but adhesiveness to plastic decreases

Engineering Contradiction:
Improvepress-formabilityVSAvoidadhesiveness
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the lubricant from conventional polyethylene wax to oxidized polyethylene wax or polyethylene glycol, which have different molecular structures and polarity characteristics. This parameter change allows the lubricant to provide adequate press-formability while maintaining adhesiveness to plastic through improved chemical compatibility with the adhesive layer.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite chemical conversion coating film containing multiple components: water-soluble resin (5-30 mass%), colloidal silica (10-60 mass%), and the specific lubricant (0.1-5 mass%). This composite structure combines the benefits of each component - the water-soluble resin provides adhesion, the colloidal silica provides corrosion resistance and surface integrity, and the oxidized polyethylene wax or polyethylene glycol provides lubrication with improved adhesive compatibility.

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If conventional lubricants are used in the chemical conversion coating film, then press-formability is maintained, but adhesiveness to plastic is insufficient

Engineering Contradiction:
Improvepress-formabilityVSAvoidadhesiveness
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent introduces a fundamental parameter change in the lubricant's chemical structure by using oxidized polyethylene wax or polyethylene glycol instead of conventional lubricants. These materials have oxygen-containing functional groups that improve chemical compatibility with polar adhesive systems, thereby enhancing adhesiveness while maintaining the lubrication function needed for press-formability.

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 metal sheet that is excellent in press-formability and adhesiveness, enabling the formation of composite members with improved weldability and adhesive strength, suitable for various applications such as automotive and domestic appliance components.

Implementation Method 1

the chemical conversion coating film contains a water-soluble resin and colloidal silica

Methodology Applied
Scientific EffectColloidal silica: Colloid

Implementation Method 2

a lubricant with carbon-oxygen bonds such as oxidized polyethylene wax

Methodology Applied
Scientific EffectLubrication: Lubrication

Data Source

PatentEP3421640B1Conversion-coated metal plate, surface-treated metal plate, composite member, and method for producing conversion-coated metal plate
Publication Date: 2023.04.19 KOBE STEEL LTD

AI summary

According to one aspect of the present invention, there is provided a chemical conversion coated metal sheet including a metal substrate and a chemical conversion coating film laminated on at least one surface of the metal substrate, in which the chemical conversion coating film contains a water-soluble resin, and a lubricant having carbon-oxygen bonds; a thickness of the chemical conversion coating film is 0.2 to 1 µm; and the lubricant includes 1 atom% or more of carbon atoms configuring the carbon-oxygen bonds relative to a total of carbon atoms contained in the lubricant.