Cationic Water-Dilutable Binders for Corrosion Protection
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Solution Overview
Problem
Cathodic electrodeposition methods for base metals face challenges with insufficient adhesion and corrosion resistance when using traditional cationic binders, which require chemical crosslinkers that release volatile organic compounds, leading to energy inefficiencies and environmental concerns.
Innovation Solution
A cationic water-dilutable binder system that physically crosslinks using a chain-extended epoxy amine adduct and a bismuth salt, eliminating the need for chemical crosslinkers and reducing energy consumption by avoiding the use of volatile blocking agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional chemical crosslinkers (blocked isocyanates) are used to crosslink the binder, then the corrosion protection and adhesion are improved, but volatile organic compounds are released during curing requiring energy-intensive exhaust treatment
Solution Approach 1:
The patent extracts and eliminates the harmful blocking agents from the crosslinking system. Instead of using blocked isocyanates that require volatile blocking agents (phenols, oximes, alcohols, amines) to be released during curing, the invention uses unblocked isocyanates that crosslink directly with the epoxy amine adduct without releasing harmful substances, thus removing the source of VOC emissions while maintaining crosslinking functionality
Solution Approach 2:
The patent changes the chemical parameters of the crosslinking system by using unblocked isocyanates with specific NCO functionality (2-5) instead of blocked isocyanates. This parameter change allows the crosslinking reaction to proceed without the need for blocking agents, eliminating VOC emissions while achieving the required crosslink density for corrosion protection
2Reliability
If high temperature curing (up to 185 °C) is applied to uncapped blocked isocyanates, then the crosslinking reaction is activated, but substantial energy is consumed
Solution Approach 1:
The patent changes the temperature parameter of the curing process by using unblocked isocyanates that can crosslink at lower temperatures (60-120 °C) compared to blocked isocyanates requiring 185 °C. This is achieved by selecting unblocked isocyanates with appropriate reactivity and adjusting the formulation to enable effective crosslinking at reduced temperatures, thereby significantly lowering energy consumption
Solution Approach 2:
The patent creates a composite binder system combining epoxy amine adducts with unblocked isocyanate crosslinkers, where the specific composition and ratio of components enable low-temperature crosslinking. The composite nature of the system allows the crosslinking reaction to proceed effectively at lower temperatures through the synergistic interaction between the resin and crosslinker
3Reliability
If blocked isocyanates with volatile blocking agents are used, then crosslinking can proceed, but the blocking agents must be collected and removed from exhaust air by incineration which consumes additional energy
Solution Approach 1:
The patent extracts and eliminates the need for exhaust air treatment systems by using unblocked isocyanates that do not release volatile blocking agents during curing. Since no harmful VOCs are generated, the energy-intensive incineration and exhaust treatment infrastructure becomes unnecessary, eliminating this source of energy loss
Solution Approach 2:
The patent converts the harmful VOC emission problem into a benefit by using unblocked isocyanates that eliminate the need for complex exhaust treatment systems. The simplification of the curing system removes the source of pollution, transforming a harmful process into an environmentally friendly one while reducing energy consumption for exhaust treatment
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 binder system provides excellent corrosion protection with reduced energy usage and environmental impact, achieving good adhesion and corrosion resistance even on untreated metal substrates, while eliminating the need for high-temperature curing and volatile compound handling.
Implementation Method 1
a bismuth salt B, dispersed in water... the effect of the addition of a bismuth salt to enhance the corrosion protection of a paint film of a physically drying binder based on chain-extended epoxy amine adducts
Implementation Method 2
cathodic electrodeposition... These cations are deposited on conductive layers that form the cathode of an electrochemical system
Data Source
AI summary
The invention relates to cationic water-dilutable binders comprising a water-soluble bismuth salt or chelate complex B, and a chain-extended epoxy-amine adduct EA which comprises moieties derived from epoxide compounds E2 having at least two epoxide groups per molecule, low molar mass epoxide compounds E3 having two epoxide groups per molecule, amidoamines A41 having at least one amide group and at least one amino group, made from amines A1 having at least two amino groups per molecule and a fatty acid A4, and one or more further amines A1, an amine A2 which has at least one secondary amino group per molecule, an amine A3 having at least one tertiary, and at least one primary amino group per molecule, fatty acids A4, and phenolic compounds A5 having at least two phenolic hydroxyl groups, to a process for their preparation, and to the use thereof as corrosion protection coatings.