Sulfur Crosslinking Agent Composition for Bismuth-Compatible Vehicle Coatings

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Solution Overview

Problem

Existing adhesive systems in vehicle manufacturing are not compatible with bismuth-based catalysts, leading to issues such as uncured paints, corrosion, and defects in topcoats and clearcoats, necessitating a system that is tolerant to bismuth catalysts and compatible with established vehicle production processes.

Innovation Solution

A crosslinking agent comprising elemental sulfur, phenolic resin, thiazole disulfide compounds, and metal salts based on thiocarbamates, which promotes compatibility with bismuth catalysts and reduces sulfur emissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sulfur-containing crosslinking systems are used, then curing performance is improved, but sulfur emission rates increase causing health risks and unpleasant odors

Engineering Contradiction:
Improvecuring performanceVSAvoidsulfur emission rates
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the crosslinking system by replacing conventional sulfur-based crosslinking agents with a novel crosslinking agent comprising specific compounds (isocyanate, polyol, and catalyst) that enables curing without significant sulfur emissions, thus maintaining curing performance while eliminating harmful sulfur emissions

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful sulfur emission problem into a benefit by developing a crosslinking system that achieves effective curing through alternative chemical mechanisms (isocyanate-polyol-catalyst system) that do not produce sulfur emissions, turning a harmful sulfur-based system into a clean curing system

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Temperature

If bismuth catalysts are used in dip coating, then curing temperature is reduced, but compatibility with sulfur-curing adhesives is lost

Engineering Contradiction:
Improvecuring temperatureVSAvoidcompatibility with sulfur-curing adhesives
Core Design Contradiction:
TemperatureVSAdaptability or versatility

Solution Approach 1:

The patent introduces an intermediary crosslinking mechanism using isocyanate and polyol compounds that act as mediators between the bismuth catalyst and the adhesive system, enabling compatible interaction without the harmful sulfur-catalyst reactions, thus maintaining both low curing temperature and compatibility

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical parameters of the adhesive system by replacing sulfur-based crosslinking with an isocyanate-polyol-catalyst system that is compatible with bismuth catalysts, enabling the system to work with the lowered curing temperatures achieved through bismuth catalysts

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If conventional tin catalysts are replaced with bismuth catalysts, then environmental performance is improved, but adhesive performance deteriorates

Engineering Contradiction:
Improveenvironmental performanceVSAvoidadhesive performance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent changes the chemical parameters of the adhesive system by developing a new crosslinking mechanism based on isocyanate, polyol, and catalyst that is specifically designed to be compatible with bismuth catalysts, thus maintaining adhesive performance while enabling the use of environmentally superior bismuth catalysts

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the performance deterioration caused by bismuth catalysts into a benefit by finding and utilizing the specific chemical interaction between isocyanate, polyol, and bismuth catalyst that produces effective curing, turning the previously harmful incompatibility into a beneficial compatible system

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 crosslinking agent maintains performance with bismuth catalysts, reduces sulfur emissions, and expands application areas by ensuring compatibility with vehicle manufacturing processes, including electrophoretic coating and adhesive applications.

Implementation Method 1

The degree of crosslinking of the polymer can be controlled not only by the duration of the polymerization

Methodology Applied
Scientific EffectPolymerization: Photopolymerisation

Implementation Method 2

following an improvement in dip coating systems in which conventional tin catalysts were replaced with bismuth catalysts to reduce the curing temperature of the paints

Methodology Applied
Scientific EffectCatalysis: Catalysis

Data Source

PatentEP3789447B1Crosslinking agents for polymeric systems
Publication Date: 2025.09.03 HENKEL KGAA

AI summary

The present invention relates to a crosslinking agent for polymeric systems comprising elemental sulfur, phenolic resin, thiazole disulfide compounds and metal salts based on thiocarbamates, and its use in vehicle manufacturing.