Electrocoat Primer with Phosphorous Resin for Unphosphated Steel

Solution Overview

Problem

Current industrial coating processes for metal articles in corrosive environments require a phosphating pretreatment step, which is complex, costly, and time-consuming, limiting the efficiency of corrosion protection for unphosphated metal substrates.

Innovation Solution

An electrocoat coating composition comprising an amine-functional phosphorylated resin with phosphorous-containing groups and specific metal oxides (such as bismuth, vanadium, manganese, and zirconium oxides) is used for electrodeposition on unphosphated metal substrates, providing enhanced corrosion protection without the need for phosphating pretreatment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If phosphating pretreatment is applied to metal substrates, then corrosion resistance is improved, but process complexity and cost increase

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidprocess complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the phosphating pretreatment function and the electrocoat priming function into a single integrated coating layer. The coating composition contains phosphorous-containing compounds (such as phosphonic acid esters or phosphate esters) that provide both the corrosion protection normally achieved through phosphating and the adhesion promotion for subsequent coatings, thereby eliminating the need for separate phosphating and priming steps.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated coating layer serves multiple functions simultaneously: it provides corrosion protection through phosphorous-containing compounds, ensures adhesion to the metal substrate, and acts as a primer for subsequent topcoats. This multi-functional coating replaces the traditional multi-step process with a single step that achieves all necessary functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If phosphating pretreatment is applied to metal substrates, then corrosion resistance is improved, but processing time increases

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent combines the phosphating pretreatment function and the electrocoat priming function into a single integrated coating layer. The coating composition contains phosphorous-containing compounds (such as phosphonic acid esters or phosphate esters) that provide both the corrosion protection normally achieved through phosphating and the adhesion promotion for subsequent coatings, thereby eliminating the need for separate phosphating and priming steps.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The phosphorous-containing compounds are incorporated into the coating composition itself, so that the corrosion protection function is built into the coating material before application. This eliminates the need for a separate preliminary phosphating treatment step, as the coating material itself provides the corrosion resistance when applied directly to the metal substrate.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If phosphating pretreatment is applied to metal substrates, then corrosion resistance is improved, but cost increases

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines the phosphating pretreatment function and the electrocoat priming function into a single integrated coating layer. The coating composition contains phosphorous-containing compounds (such as phosphonic acid esters or phosphate esters) that provide both the corrosion protection normally achieved through phosphating and the adhesion promotion for subsequent coatings, thereby eliminating the need for separate phosphating and priming steps.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the essential corrosion protection function from the separate phosphating pretreatment step and incorporates it directly into the electrocoat priming composition. By taking out the phosphorous-containing compounds and integrating them into the coating material, the process eliminates unnecessary steps while maintaining the corrosion resistance function.

Inventive Principle:

Principle #2Taking out (Extraction)

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

This approach significantly improves corrosion resistance on unphosphated metallic substrates, such as cold-rolled steel, by interacting phosphorous-containing groups with metal oxides, offering unexpectedly strong anticorrosive effectiveness and simplifying the coating process by eliminating the phosphating step.

Implementation Method 1

During electrodeposition, coating material containing the ionically-charged resin having a relatively low molecular weight is deposited onto a conductive substrate by submerging the substrate in the electrocoat bath and then applying an electrical potential between the substrate and a pole of opposite charge

Methodology Applied

Scientific EffectElectrodeposition: Electrodeposition

Implementation Method 2

The charged coating material migrates to and deposits on the conductive substrate

Methodology Applied

Scientific EffectElectrophoresis: Electrophoresis

Implementation Method 3

the electrocoat coating provides excellent corrosion protection... by interacting phosphorous-containing groups with metal oxides

Methodology Applied

Scientific EffectChemical interaction between phosphorous groups and metal oxides: Chemical Bonding

Data Source

PatentUS8961768B2Metal containing integrated electrocoat for better corrosion resistance

Publication Date: 2015.02.24 BASF CORPORATON

AI summary

An aqueous electrodeposition coating composition comprising (a) a metal oxide selected from the group consisting of bismuth oxide, vanadium oxide, manganese oxide, cobalt oxide, zinc oxide, strontium oxide, yttrium oxide, molybdenum oxide, zirconium oxide, lanthanum oxide, oxides of the lanthanide series of elements, and combinations of these and (b) a cathodically electrodepositable binder, the binder comprising an amine-functional phosphorylated resin, provides corrosion protection equivalent to that obtained by the conventional phosphate pretreatment-electrodeposition coating process.