Multilayer Coating Film Composition for Low-Temperature 3C1B Curing

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Solution Overview

Problem

Existing methods for forming multilayer coating films on motor vehicle bodies using a 3C1B process face issues with layer mixing and inadequate adhesion to external components, especially when using aqueous coating materials and low thermal curing temperatures, leading to poor adhesion to double-sided tapes and insufficient gasoline and water resistance.

Innovation Solution

A method involving a specific two-component clear coating material, using a hydroxy group-containing acrylic resin with a surface conditioner, and an aqueous base coating material, which includes an acrylic urethane resin, to ensure good adhesion and resistance even at low thermal curing temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by stationary object

If a 3C1B process is used to reduce energy consumption, then the thermal curing temperature is reduced, but adhesion to double-sided tape deteriorates

Engineering Contradiction:
Improveenergy consumptionVSAvoidadhesion to double-sided tape
Core Design Contradiction:
Use of energy by stationary objectVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the clear coating material by incorporating specific functional additives and adjusting the resin formulation to enable effective crosslinking and adhesion formation even at reduced thermal curing temperatures of 75-100°C, thus maintaining reliability while reducing energy consumption

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite clear coating material system comprising multiple resin components (acrylic resin, polyester resin), crosslinking agents, and functional additives that work synergistically to provide both low-temperature curability and excellent adhesion properties to double-sided tapes

Inventive Principle:
Principle #40Composite materials

2Use of energy by stationary object

If a 3C1B process is used to reduce energy consumption, then the thermal curing temperature is reduced, but gasoline resistance deteriorates

Engineering Contradiction:
Improveenergy consumptionVSAvoidgasoline resistance
Core Design Contradiction:
Use of energy by stationary objectVSObject-affected harmful factors

Solution Approach 1:

The invention modifies the chemical structure and composition parameters of the coating film by using specific resin systems with appropriate molecular weights and functional groups that form dense crosslinked networks, providing excellent gasoline resistance even when cured at low temperatures

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention employs a composite resin system combining acrylic and polyester resins with crosslinking agents that create a chemically resistant network structure, ensuring gasoline resistance is maintained despite reduced thermal curing conditions

Inventive Principle:
Principle #40Composite materials

3Use of energy by stationary object

If a 3C1B process is used to reduce energy consumption, then the thermal curing temperature is reduced, but water resistance deteriorates

Engineering Contradiction:
Improveenergy consumptionVSAvoidwater resistance
Core Design Contradiction:
Use of energy by stationary objectVSObject-affected harmful factors

Solution Approach 1:

The invention adjusts the resin composition parameters including hydroxyl value, carboxyl value, and molecular weight to optimize the coating film's hydrophobicity and crosslinking density, achieving excellent water resistance at low curing temperatures

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite resin formulation with acrylic and polyester components that provide complementary properties for water resistance, creating a synergistic effect that maintains protective performance under reduced thermal curing conditions

Inventive Principle:
Principle #40Composite materials

4Object-generated harmful factors

If an aqueous base coating material is used to reduce VOC usage, then environmental performance is improved, but layer mixing between intermediate and base coating films occurs

Engineering Contradiction:
ImproveVOC usageVSAvoidlayer mixing
Core Design Contradiction:
Object-generated harmful factorsVSStability of the object's composition

Solution Approach 1:

The invention optimizes the surface tension, viscosity, and composition parameters of the aqueous base coating material to control its interaction with the intermediate coating film, preventing unwanted layer mixing while maintaining environmental benefits

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates distinct chemical and physical properties at the interface between coating layers through controlled composition gradients and surface modification, ensuring proper layer separation and stability in the multilayer structure

Inventive Principle:
Principle #3Local quality

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 method achieves a coating film with excellent adhesion to double-sided tapes, good gasoline resistance, and water resistance, while maintaining smoothness and gloss, even at curing temperatures of 75-100°C, addressing the issues of layer mixing and adhesion.

Implementation Method 1

thermally curing... at low thermal curing temperatures... curing temperatures of 75-100°C

Methodology Applied
Scientific EffectThermal curing: Heating

Implementation Method 2

using a hydroxy group-containing acrylic resin with a surface conditioner... achieves a coating film with excellent adhesion to double-sided tapes

Methodology Applied
Scientific EffectSurface modification: Adsorption

Implementation Method 3

sequentially coating an intermediate coating material, a base coating material and a clear coating material

Methodology Applied
Scientific EffectCoating deposition: Deposition (physical)

Data Source

PatentUS12545802B2Method for forming multilayer coating film
Publication Date: 2026.02.10 BASF COATINGS GMBH

AI summary

Disclosed herein is a method for forming a multilayer coating film by sequentially coating an intermediate coating material composition, a base coating material composition and a clear coating material composition on a metal for a motor vehicle body or resin material and then thermally curing the compositions, where the clear coating material composition is obtained by mixing a main agent (A) and a curing agent (B).