Reactive Sol-Gel Ink for Coil Coating Adhesion
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Solution Overview
Problem
Existing coil coating processes face challenges in achieving superior adhesion, flexibility, and weather resistance for deformable metallic substrates, particularly under moderate cross-linking conditions, while maintaining the required properties for outdoor applications.
Innovation Solution
A reactive sol-gel ink comprising a sol-gel resin composition made from a mixture of epoxy functionalized alkoxy-silane, trialkoxysilane, and aluminum alkoxide, with specific molar ratios and acidic catalysts, which allows for covalent bonding with primer and topcoat layers, enhancing adhesion and flexibility while reducing thermal cross-linking requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature thermal cross-linking is used to achieve superior adhesion and weather resistance, then the coating properties are improved, but the flexibility and elasticity of the coating structure deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the coating system by introducing reactive sol-gel ink containing epoxy-functionalized silanes that can cross-link at lower temperatures. This allows achieving adequate cross-linking density for adhesion and weather resistance without requiring temperatures above 180°C, thereby preserving the flexibility and elasticity of the polymer matrix.
Solution Approach 2:
The patent creates a composite coating system combining organic polymer matrices with inorganic sol-gel derived networks. The sol-gel components provide cross-linking for adhesion and durability, while the organic polymer phase maintains flexibility and elasticity. This hybrid composite structure resolves the contradiction between hardness/adhesion and flexibility.
2Reliability
If strongly swelling high-boiling solvents are used to strengthen physical bonding between layers, then the adhesion is improved, but the long-term resistance and elasticity of the overall structure deteriorate
Solution Approach 1:
The patent replaces physical bonding mechanisms (which rely on solvent swelling and evaporation) with chemical bonding mechanisms. The reactive sol-gel ink contains epoxy groups that form covalent bonds with hydroxyl groups on the metal substrate and with carboxyl groups in the polymer layers, providing permanent chemical adhesion that does not degrade over time.
3Productivity
If multiple coating layers are applied in a continuous process to achieve uniform surface quality and controlled thickness, then the manufacturing efficiency is improved, but the complexity of the process increases
Solution Approach 1:
The patent combines multiple coating functions into a single reactive sol-gel ink formulation. The ink simultaneously provides color pigmentation, adhesion promotion through epoxy-silane chemistry, weather resistance through cross-linked network formation, and flexibility through the polymer-sol-gel hybrid structure. This consolidation simplifies the manufacturing process while maintaining high productivity.
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 sol-gel ink provides superior pot life and stability, enabling effective coating and printing on deformable metallic substrates with improved adhesion, flexibility, and weather resistance, suitable for outdoor applications without the need for high-temperature curing.
Implementation Method 1
a hydrolysate obtainable by reacting a mixture comprising at least one epoxy functionalized alkoxy-silane, at least one further trialkoxysilane and at least one aluminum alkoxide with water
Implementation Method 2
The sol-gel resin composition comprises a) 35 to 65 wt% of a hydrolysate obtainable by reacting a mixture comprising at least one epoxy functionalized alkoxy-silane, at least one further trialkoxysilane and at least one aluminum alkoxide with water
Data Source
AI summary
The present invention relates to a reactive sol-gel ink for printing a metallic substrate, preferably for a coil coating process, comprising 10 to 30 wt% of a sol-gel resin composition and at least one pigment, preferably at least one yellow pigment, at least one purple pigment, at least one cyan pigment or at least one black pigment. The sol-gel ink of the present invention can be used in a digital print process, preferably using ink jet means, as a mediator of covalent bonds between a print layer formed by the sol-gel ink and metal oxides and/or metal hydroxides on the metallic substrate and/or hydroxyl groups comprised in a base coat layer covering at least partially the metallic substrate and/or hydroxyl groups comprised in a top coat composition covering at least partially the sol-gel ink.