Silane Crosslinked Epoxy Coatings for Scratch and Mar Resistance
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Solution Overview
Problem
Conventional clearcoat compositions for automotive surfaces face challenges in achieving simultaneous high scratch and mar resistance, as well as self-healing reflow properties, which are typically mutually contradictory, leading to unsatisfactory performance in either surface hardness or gloss recovery.
Innovation Solution
A 2K solvent-borne coating system comprising an epoxy component with specific silane compounds and a carboxylic acid resin, which are partially hydrolyzed and condensed to form structures with epoxy side chains, providing enhanced crosslinking and storage stability, allowing for improved scratch and mar resistance while maintaining reflow properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional clearcoat compositions are used to achieve high scratch and mar resistance, then surface hardness is improved, but reflow properties and gloss recovery deteriorate
Solution Approach 1:
The patent employs a composite clearcoat system combining epoxy resin, polyurethane resin, and silane crosslinking agents. This multi-component composite formulation creates a synergistic effect where the epoxy provides base hardness, the polyurethane contributes flexibility and reflow capability, and the silane crosslinks enhance both scratch resistance and maintain reflow properties, thereby resolving the contradiction between hardness and reflow performance
Solution Approach 2:
The patent utilizes silane crosslinking chemistry to change the molecular structure parameters of the coating. The silane groups form crosslinks that increase the gel fraction and modify the polymer network architecture, enabling the coating to achieve high scratch resistance while preserving the chain mobility needed for reflow and gloss recovery
2Strength
If conventional clearcoat compositions are used to achieve high scratch and mar resistance, then surface hardness is improved, but gloss retention and surface appearance deteriorate
Solution Approach 1:
The composite formulation combining epoxy, polyurethane, and silane components creates a balanced coating network that maintains surface smoothness and gloss while providing scratch resistance. The specific interaction between these components prevents excessive crosslinking density that would cause surface roughening, thereby preserving gloss retention
3Ease of manufacture
If conventional clearcoat compositions are used to achieve improved reflow properties, then gloss recovery is improved, but scratch and mar resistance deteriorate
Solution Approach 1:
The silane crosslinking modifies the polymer network parameters to create a dual-character coating: the crosslinks provide structural integrity for scratch resistance, while the specific crosslink density and chemistry maintain the chain mobility required for reflow and gloss recovery, achieving both properties simultaneously
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 coating system achieves significant improvements in scratch and mar resistance, with high gloss retention and reflow gloss recovery, demonstrating a synergistic effect that enhances both hardness and reflow properties, outperforming conventional epoxy-acid clearcoat coatings.
Implementation Method 1
compounds of formula (I)... wherein partial hydrolysis and condensation provides structures containing epoxy side chains
Implementation Method 2
compounds of formula (I)... wherein partial hydrolysis and condensation provides structures containing epoxy side chains
Implementation Method 3
The top-coating compositions may include various additives or chemical modifications to enhance resistance performance to UV degradation, water spotting, scratching and marring... Different type of coating compositions have varying reflow character depending upon the chemical nature of the resin, the curing agent employed and other additives present
Data Source
AI summary
Described herein is a 2K solvent borne coating system. The coating system includes an epoxy component (A), including: i) an epoxy resin; ii)—a solvent; iii)—at least one compound of formula (I):[(ER)x(R′O)y(HO)z(R″)t(SiO(4-x-y-z-t)]m (I)and/or oligomer or polymer compounds of the compound of formula (I), and iv)—optionally, at least one non-catalytic additive; and an acid resin component (B), including: an carboxylic acid resin;a solvent; optionally, at least one catalyst; and optionally, at least one additive. Also described herein are a 2K coating composition, a method to coat an automotive substrate with the composition, and a scratch and mar resistant coated surface of the 2K coating composition.