Water-Based Coating Composition for 3C1B Automotive Finish
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Solution Overview
Problem
Current 3-coat, 1-bake systems for automobile coatings face challenges in achieving simultaneous excellent chipping resistance, water resistance, smoothness, and distinctness of image due to layer mixing issues.
Innovation Solution
A water-based coating composition comprising an acrylic resin emulsion with a core-shell structure, a coating film-forming resin, and a curing agent, specifically including 7-60% acrylic resin, 10-60% coating film-forming resin, and 10-50% curing agent, with the acrylic resin having a core section with 0.1-10% polymerizable unsaturated monomers and hydroxyl values of 50-200 mgKOH/g, and a shell section with 50-200 mgKOH/g, along with a curing agent like amino resin or blocked polyisocyanate, is used in a 3C1B system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a 3C1B system is used to eliminate the bake curing step after intercoat material application, then energy consumption is reduced, but layer mixing between intercoating film and base coating film occurs, lowering smoothness and distinctness of image
Solution Approach 1:
The patent applies preliminary action by incorporating a curing agent into the base coating material itself, allowing the base coating to cure partially or fully before the clear coating is applied. This preliminary curing of the base coating prevents layer mixing with the clear coating, maintaining smoothness and image distinctness while still using a 3C1B energy-saving system.
Solution Approach 2:
The patent changes the parameter of curing timing and degree by adjusting the curing agent content and type in the base coating material. By controlling the curing progress at different stages, the system achieves both energy efficiency of 3C1B and quality requirements for smoothness and image distinctness.
2Reliability
If water-based intercoat material composition with specific talc and silane coupling agent is used, then chipping resistance is improved, but the formulation complexity increases
Solution Approach 1:
The patent applies universality by developing a base coating material that simultaneously provides chipping resistance, adhesion promotion, and curing functionality. The base coating material with curing agent can serve multiple functions, reducing the need for separate specialized additives and simplifying the overall formulation while maintaining excellent chipping resistance.
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 solution enables the formation of a multilayer coating film with enhanced chipping resistance, smoothness, and distinctness of image by optimizing the composition and curing process in a 3C1B system.
Implementation Method 1
a crosslinking agent (c)... whereby curing reactivity between the copolymer resin emulsion and the curing agent is increased
Implementation Method 2
a copolymer resin emulsion obtained by emulsion polymerization of a monomer (a)
Implementation Method 3
the obtained 3-layer multilayer coating film is simultaneously heat cured
Implementation Method 4
step (4): a step of bake curing the multilayer coating film formed in steps (1) to (3)
Implementation Method 5
the hydroxyl value of the core section is 50 to 200 mgKOH/g and the hydroxyl value of the shell section is 50 to 200 mgKOH/g
Data Source
AI summary
A water-based coating composition and method for forming a multi-layer coating film by which it is possible to form a coating film 5 having excellent smoothness, image clarity, and chipping resistance in a 3C1B format. The composition is characterized by containing 7 to 60 mass % of an acrylic resin emulsion (a), 10 to 60 mass % of a film-forming resin (b), and 10 10 to 50 mass % of a curing agent (c), on the basis of the total mass of the solid resin content in the composition; the acrylic resin emulsion (a) having a core/shell structure where the core section contains, as a copolymer component, 0.1 to 10 mass % of a polymerizable unsaturated 15 monomer having two or more polymerizable unsaturated groups in one molecule, on the basis of the total mass of monomer of the core section, and the hydroxyl value of the core section is 50 to 200 mgKOH/g, and the hydroxyl value of the shell section is 50 to 200 mgKOH/g.