In-Mold Coating Hardener for Fast Curing and Chemical Resistance
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Solution Overview
Problem
Current aqueous in-mold coating systems for automobile interior parts do not meet the requirements of the automotive industry in terms of curing speed, color stability, and chemical resistance, particularly against cleaning agents, as specified by standards like the Daimler-Chrysler standard DBL 5381.
Innovation Solution
A 2-component paint formulation using special isocyanate-functional hardener mixtures and water-thinnable resins, with a composition of 40-90% aqueous non-functional or hydroxy-functional resin dispersion and 5-40% hardener component, consisting of trimersiate mixtures based on aliphatic and/or cycloaliphatic diisocyanates, containing at least 10% iminooxadiazinedione type compounds, which allows for improved processing time and curing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional aqueous in-mold coating systems are used, then the coating process is environmentally friendly (solvent-free), but the curing speed is too slow and chemical resistance is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the hardener component by incorporating specific catalysts (metal salts like zinc, calcium, barium) and co-hardeners (polyisocyanates with specific NCO content) into the aqueous 2K paint formulation. This parameter modification enables the coating to achieve both fast curing speed and high chemical resistance against cleaning agents, resolving the contradiction between environmental friendliness and performance requirements.
2Manufacturing precision
If the processing time is extended to allow proper application, then the coating quality improves, but the cycle time increases and productivity decreases
Solution Approach 1:
The patent creates a dynamic curing process where the coating initially remains workable for adequate application time, then rapidly cures under heat treatment (80-120°C). The formulation with specific hardener ratios and catalysts provides a time-dependent transformation from a flexible application state to a fixed cured state, enabling both good coating quality and reduced cycle time by optimizing the transition point.
3Productivity
If faster curing is achieved through formulation modification, then the cycle time decreases, but the adhesion to polyurethane elastomer deteriorates
Solution Approach 1:
The patent applies local quality by creating different functional zones within the coating formulation: the resin dispersion provides adhesion to the polyurethane elastomer substrate, while the specially formulated hardener component with catalysts provides rapid curing. This spatial and functional differentiation within the coating layers allows simultaneous achievement of good adhesion and fast curing without compromise.
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 paint formulation provides significantly improved chemical and color resistance, enabling longer processing times with faster curing, and produces polyurethane skins with excellent surface quality, abrasion, UV, and cleaning agent resistance.
Implementation Method 1
aqueous 2-component paint formulations, in particular 2-component polyurethane paint formulations, based on special isocyanate-functional hardener mixtures and water-dilutable resins
Implementation Method 2
based on special isocyanate-functional hardener mixtures containing catalysts
Implementation Method 3
water-dilutable resins
Data Source
AI summary
The invention relates to an in-mold coating method for producing molded parts with the aid of aqueous 2-component lacquer formulations containing: A) 40 to 90 percent by weight (relative to the entire formulation) of at least one aqueous non-functional or hydroxy-functional resin dispersion, B) 5 to 40 percent by weight (relative to the entire formulation) of at least one hardener component having a free isocyanate group concentration of 10 to 23 percent by weight relative to the solid resin, and C) fillers, pigments, auxiliaries, and additives, the total percentage by weight amounting to 100 percent. The invention is characterized in that component B) is essentially composed of trimer mixtures based on aliphatic and/or cycloaliphatic diisocyanates containing proportionate amounts of isocyanurate-type compounds (type I) and iminooxadiazine dione-type compounds (type II), at least 10 percent by weight of iminooxadiazine dione-type compounds (type II) relative to the isomeric trimer structures being provided.