Polysilane Shop Primer for Steel Adhesion and Welding

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Solution Overview

Problem

Alkali metal silicate-based waterborne shop primers for steel surfaces are high in pH, leading to adhesion issues with subsequent coatings when exposed to water, and require specialized equipment, limiting their application and compatibility with conventional coatings.

Innovation Solution

A polysilane-based shop primer composition incorporating zinc oxide or zirconium hydrogen phosphate as accelerators and microspheres, which provides fast curing, excellent weldability, abrasion resistance, and compatibility with various coatings without the need for extensive pretreatment, while maintaining low VOC levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If alkali metal silicate binders are used in waterborne shop primers, then quick drying time and low VOC are achieved, but high pH causes adhesion loss and blistering of subsequent coatings when exposed to water

Engineering Contradiction:

Improvedrying timeVSAvoidadhesion of subsequent coatings

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent changes the pH parameter of the binder from high (alkali metal silicate, pH 11-12) to neutral or slightly acidic (polysilane sol, pH 3-6.5), eliminating the adhesion problem while maintaining quick drying properties through the silane condensation mechanism

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces expensive specialized equipment requirements with conventional application equipment by using a neutral pH polysilane binder that is compatible with standard metal surfaces and application tools, eliminating the need for specialized non-metal equipment

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Loss of time

If alkali metal silicate binders are used, then low VOC and quick drying are achieved, but specialized production and application equipment is required

Engineering Contradiction:

Improvedrying timeVSAvoidequipment requirements

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent changes the pH parameter from highly alkaline to neutral/slightly acidic, which allows the use of conventional metal equipment for both production and application, eliminating the need for specialized non-metal equipment while maintaining quick drying performance

Inventive Principle:

Principle #35Parameter changes

3Reliability

If organic resin binders are used in shop primers, then good corrosion protection is achieved, but the binder decomposes from weld heat causing pores in weld seams

Engineering Contradiction:

Improvecorrosion protectionVSAvoidweld porosity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces organic resin binders with inorganic polysilane binders that are thermally stable and do not decompose at welding temperatures, eliminating weld porosity while maintaining corrosion protection through the zinc-containing formulation and silane network structure

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Reliability

If high pH alkali silicate primers are applied to steel, then temporary corrosion protection is achieved, but thorough washing or removal is required before overcoating

Engineering Contradiction:

Improvecorrosion protectionVSAvoidovercoating process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the pH parameter from high (11-12) to neutral or slightly acidic (3-6.5), creating a primer that is compatible with subsequent coatings without requiring washing or removal, simplifying the overcoating process while maintaining corrosion protection

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary neutralization of the binder pH before application, preventing the adhesion problems that would require subsequent washing or removal steps, allowing direct overcoating after simple surface preparation

Inventive Principle:

Principle #10Preliminary action

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 polysilane-based shop primer composition ensures rapid drying, improved water resistance, reduced pore formation, and enhanced weldability, allowing direct overcoating without adhesion loss, even when exposed to water, and can be applied using conventional equipment.

Implementation Method 1

a polysilane sol obtained by the condensation reaction of at least one silane and comprising a 2D or 3D network of siloxane {Si-O-Si} bonds and free silanol functionalities

Methodology Applied

Scientific EffectCondensation reaction:

Implementation Method 2

at least one accelerant such as zinc oxide or zirconium hydrogen phosphate

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentEP3408335B1Shop primer

Publication Date: 2023.01.18 JOTUN AS

AI summary

An aqueous shop primer comprising: (A) 25 to 80 wt% of a polysilane sol; (B) 0.5 to 15 wt% of an accelerator selected from at least one of zinc phosphate, zinc oxide, calcium strontium zinc phosphosilicate, zirconium hydrogen phosphate, iron phosphide, calcium zirconate, barium zirconate, zirconium nitride, zinc titanate and iron(II) titanate; (C) 15 to 40 wt% of at least one anticorrosive pigment; (D) 0.5 to 10 wt% microspheres.