Modern automotive electrocoating systems must uniformly deposit protective films across complex vehicle geometries while managing current densities of 0.1-2.0 mA/cm². These systems process hundreds of vehicle bodies daily through multi-stage tanks, where maintaining precise paint chemistry, temperature control between 26-32°C, and uniform electrical field distribution directly impacts coating quality and throughput.

The fundamental challenge lies in balancing coating thickness uniformity, throw power into recessed areas, and film properties while minimizing energy consumption and waste generation in high-volume production environments.

This page brings together solutions from recent research—including advanced resin chemistries with improved throwing power, multi-step processes combining electrodeposition with powder coating, sequential low-temperature curing methods, and water-based coating systems. These and other approaches focus on achieving consistent film quality while reducing environmental impact and processing costs in automotive paint operations.

1. Water-Based Two-Component Mid-Coat Paint with Hydroxyl-Free Polyurethane and Hydroxyl-Containing Acrylate Dispersions for Synergistic Cross-Linking

BEIJING YULIN CHEMICAL CO LTD, 2024

Water-based two-component mid-coat paint for automotive applications that enables construction under extreme environmental conditions. The paint combines a hydroxyl-free polyurethane dispersion with an aqueous hydroxyl-containing acrylate dispersion, achieving enhanced adhesion and film properties through synergistic cross-linking. The dispersion formulation balances rapid drying and thickening characteristics with improved solubility and water resistance. The paint exhibits excellent performance in high-temperature, low-humidity environments while maintaining smooth surface finish and excellent mechanical properties.

2. Water-Based Two-Component Polyurethane Topcoat with Hydroxyl and Polycarbonate-Containing Aliphatic Anionic Dispersions

BEIJING YULIN CHEMICAL CO LTD, 2024

Water-based two-component polyurethane topcoat for automotive coatings that addresses the challenges of high-temperature, high-humidity environments. The coating combines a hydroxyl-containing aqueous dispersion with an aqueous polycarbonate-containing aliphatic anionic polyurethane dispersion, achieving superior performance in sagging resistance, thermal stability, and water resistance. The dispersion is formulated with a specific balance of surfactants, defoamers, and rheological agents that enable optimal film formation and leveling properties. The coating can be applied as a single-component system or as a combination of the dispersion and a conventional clearcoat.

CN118755373A-patent-drawing

3. Method for Vehicle Body Coating Using Sequential Low-Temperature Primer and Base Coat Curing

VOLKSWAGEN AG, 2024

A method for painting vehicle bodies and components through a novel two-step process that reduces production energy while maintaining high-quality finishes. The process involves applying a phosphating or silane layer to the vehicle surface, followed by a primer application step using cathodic dip painting. The primer is then cured at lower temperatures (90°C) before applying a base coat, which is cured at a higher temperature (125°C). This sequential curing approach enables precise control over paint thickness and finish characteristics without requiring high-temperature curing steps, thereby significantly reducing energy consumption compared to conventional processes.

4. Method for Producing Multicoat Paint Systems Using Polyamide-Based Aqueous Dispersion Basecoat and Wet-on-Wet Clearcoat Application

BASF COATINGS GMBH, 2024

A method for producing multicoat paint systems by producing a basecoat directly on the substrate, followed by a clearcoat directly on top, with a curing step after application. The process involves applying a basecoat material comprising color and/or effect pigments, which is either an aqueous dispersion (D1) or an aqueous dispersion (D2) of polyamide (PA) with acid number 15-60 mg KOH/g or polyamide (PA) with acid number 15-60 mg KOH/g and amide wax (AW), directly to the substrate. The basecoat material is then flashed and dried before applying the clearcoat, which is cured through a wet-on-wet process. This approach eliminates the need for separate curing steps between basecoat and clearcoat, achieving higher film thicknesses and improved properties compared to conventional multicoat production methods.

US11896998B2-patent-drawing

5. Water-Based Acrylic Resin Midcoat Paint System with Single-Component High-Solid Composition and Layered Application

NIPPON PAINT CHINA CO LTD, 2023

High-solid three-coat and one-baking mid-coat paint for automobiles based on water-based acrylic resin, featuring a single-component midcoat. The paint combines a water-based acrylic emulsion with a polyurethane dispersion, achieving a solid content of 34-44% while maintaining excellent appearance performance, stone impact resistance, and mechanical properties. The midcoat is applied in three layers, with the first layer being a water-based coating, followed by a flash-dried layer, and then a baking layer. This innovative approach enables a midcoat with improved performance characteristics compared to conventional three-coat systems.

6. Automotive Body Coating Method with Multi-Step Powder Coating and Electrophoresis Process

DONGFENG AUTO GROUP CO LTD, Dongfeng Motor Group Co., Ltd., 2023

Automotive body coating method that reduces VOC emissions through a multi-step process involving pretreatment, electrophoresis, electrophoresis drying, electrophoresis polishing, and coating application. The method employs powdery coatings A and C, with A being powdery paint and C being powder varnish, which are sprayed onto the vehicle body followed by subsequent steps of electrophoresis drying, polishing, and coating application. The process ensures consistent color tone and gloss while maintaining chemical resistance and corrosion protection properties.

7. Method for Sequential Application and Heat-Curing of Multi-Layer Coating Film Using Curable Resin Composition

NISSAN MOTOR, 2022

A method for forming a multi-layer coating film using a curable resin composition for paints. The method involves sequential application and heat-curing of intermediate coating paint, base coating material, and clear coating material. The intermediate coating paint, base coating material, and clear coating material are applied in that order, with the intermediate coating paint having a temperature range of 10-40°C and relative humidity of 65-85%. The clear coating material is cured at a temperature of 100°C or less. The method enables the formation of a multi-layer coating film with improved adhesion and appearance characteristics compared to conventional multi-layer coating methods.

8. Water-Based Automotive Paint System with Core-Shell Acrylic Emulsion and Integrated Single-Step Application Process

邦弗特新材料股份有限公司, BANFERT NEW MATERIALS CO LTD, 2022

A water-based automotive paint system that enables integrated application of the paint to both body panels and exterior parts through a single-step process. The system consists of a water-based paint comprising a core-shell acrylic emulsion with controlled water content, and a curing agent that enables the paint to perform both wet-on-wet and low-temperature curing. The curing agent facilitates the formation of a cross-linked polymer network that enables the paint to meet the requirements of both wet-on-wet and low-temperature baking processes. The paint can be applied through a single-step process that combines pretreatment, electrophoresis primer treatment, and a specialized spraying and welding process.

9. High-Solid Varnish Composition with High-Etherification Amino Resins and Conductive Additives

天津科瑞达涂料化工有限公司, TIANJIN COSCO KANSAI PAINT AND CHEMICALS CO LTD, 2021

High-solid automotive finishing varnishes that achieve VOC emissions below 420g/L through a novel composition of high-solid acrylic, polyester, and n-butanol-etherified amino resins. The varnishes contain a high-etherification degree n-butanol-etherified amino resin that replaces the traditional anti-sagging resin, enhancing paint film stability. The varnishes also incorporate conductive additives and a specific viscosity adjustment process to optimize performance while maintaining low VOC emissions.

10. Water-Based Paint System with Hydrophobic and Hydrophilic Component Blend for Vehicle Undercarriage

HEBEI CHENYANG INDUSTRY AND TRADE GROUP CO LTD, 2021

A water-based, all-in-one paint system for vehicle undercarriage that combines excellent corrosion protection, adhesion, and durability. The paint film is formulated with a unique blend of hydrophobic and hydrophilic components that provide superior wetting and bonding properties, while maintaining thermal stability and flexibility. The system is designed to be environmentally friendly, with VOC-free formulation and a low-VOC curing process. The paint provides comprehensive protection for vehicle undercarriage components while maintaining a smooth, comfortable finish.

11. Method for Forming Multilayer Coating Films Using Single-Step Curing of Base and Water-Based Intermediate Coatings

KANSAI PAINT CO LTD, Honda Motor Co., Ltd., HONDA MOTOR CO LTD, 2021

Method for forming multilayer coating films with improved image quality, smoothness, and chipping resistance through a single-step curing process. The method involves applying a base coating composition, followed by a water-based intermediate coating, and then curing the intermediate coating before applying a clear coating. The intermediate coating is preheated only once, eliminating the need for separate intermediate coating steps. This single-step approach enables simultaneous curing of the base and intermediate coatings, resulting in a multilayer film with enhanced image quality, reduced chipping, and superior mechanical properties.

12. Method for Producing Multicoat Paint Systems with Integrated Surfacer and Topcoat Curing

BASF COATINGS GMBH, 2019

A method for producing multicoat paint systems that enables rapid, cost-effective production of complex automotive coatings. The process involves producing a single coating system comprising a surfacer and topcoat, where the surfacer is cured to form a cross-linked film. The topcoat is then cured to form a second cross-linked film. This single-step process eliminates the need for sequential curing steps and enables the production of coatings with improved properties compared to traditional wet-on-wet methods.

13. Acrylic Polymer Latex Emulsion with Alkylphenol-Formaldehyde Initiator and Tertiary Amine Co-Initiator for Electrocoating Applications

GUANGDONG HENGGUANG NEW MATERIAL TECH CO LTD, 2019

Waterborne acrylic emulsion for automotive electrocoating finish paint that provides superior adhesion and wet film properties. The emulsion comprises an aqueous dispersion of an acrylic polymer latex, a specific type of initiator, and a co-initiator, wherein the initiator is an alkylphenol-formaldehyde resin and the co-initiator is a tertiary amine. The emulsion demonstrates improved water resistance, film adhesion, and leveling performance compared to conventional waterborne acrylics, particularly when applied over electrocoated substrates.

14. Waterborne Polyester Resin Automotive Coating with Hydroxyl and Ester Functionalities for Intermediate Layer

上海大众联合汽车改装有限公司, SHANGHAI VOLKSWAGEN AUTOMOTIVE MODIFIED CO., LTD, 2018

Waterborne polyester resin-based automotive coating for improving vehicle body surface finish through a novel intermediate layer. The coating composition comprises a waterborne polyester resin with specific weight distribution, particularly containing hydroxyl groups and ester functionalities, which enables enhanced gloss retention and reflective properties while maintaining low VOC emissions.

15. Water-Borne Automotive Coating Composition with Polyester, Acrylic, and Urethane Resins and Melamine Curing Agent

KCC CORP, KCC Corporation, 2018

Water-borne automotive coating composition and method for achieving improved paint performance through enhanced dispersion and adhesion. The composition comprises a polyester resin, acrylic resin, aqueous urethane resin, and melamine curing agent, with a dispersible urethane resin having a molecular weight below 20,000 and a dispersing agent. The composition is formulated to achieve optimal dispersion and adhesion properties for automotive coatings, particularly in oil-based systems, while maintaining superior wetting and drying characteristics.

KR101857857B1-patent-drawing

16. Aqueous Polyurethane-Polyurea Dispersion with Specified Particle Size and Gel Fraction for Basecoat Applications

BASF COATINGS GMBH, 2018

Aqueous polyurethane-polyurea dispersion (PD) for basecoat materials in multicoat paint systems that enhances performance properties through improved rheological behavior and structural viscosity. The dispersion comprises polyurethane-polyurea particles with average particle size of 40-2000 nm and gel fraction of at least 50%. The dispersion enables high solids content aqueous basecoat formulations while maintaining excellent storage stability and rheological properties.

US2018002476A1-patent-drawing

17. Automotive Coating System with Multi-Layered Application and Proprietary Primer, Paint, and Varnish Formulations

WUHU CHUNFENG NEW MATERIALS CO LTD, 2017

A specialized automotive coating that enhances the durability, appearance, and performance of vehicle bodies through a multi-layered application process. The coating comprises a primer, a paint, and a varnish, which are applied in a specific sequence to achieve exceptional weather resistance, water repellency, and adhesion. The coating system features a proprietary primer formulation with specialized additives, a high-performance paint with enhanced gloss retention, and a specially developed varnish that maintains uniform dispersion and leveling during application. The coating system is formulated to ensure complete curing, solvent-free residue, and needle-free bubbles. The coating provides excellent fullness, gloss, and surface finish characteristics, making it ideal for high-performance vehicles.

CN107057536A-patent-drawing

18. Single-Component Waterborne Paint with Anionic Polyurethane Dispersion and Integrated Additives

Yatu Advanced Materials Co., Ltd., YATU HIGH-TECH MATERIALS CO LTD, 2017

A single-component waterborne paint for automotive applications that addresses the environmental concerns of traditional solvent-based coatings. The paint comprises an anionic polyurethane dispersion as the primary resin component, which provides excellent water resistance, chemical resistance, and weather resistance properties. The dispersion is synthesized through a single-step process involving the combination of an anionic polyurethane aqueous dispersion with a substrate wetting agent, defoamer, and thickener. The dispersion is then formulated with additives such as surfactants and wetting agents to enhance its performance characteristics. The resulting paint can be formulated into various coatings, including primer, medium coat, undercoat, and varnish, and can be used in automotive applications where VOC emissions are a critical concern.

19. Automotive Paint System with Integrated Basecoat and Clearcoat Layers

TIANJIN COLOUROAD COATING AND CHEMICALS CO LTD, 2016

A paint system for automotive applications that eliminates the need for a separate primer coat. The system comprises a basecoat layer comprising a combination of resins, pigments, and UV absorbers, and a clearcoat layer comprising a combination of resins and nano-materials. The basecoat layer provides UV protection and adhesion to the substrate, while the clearcoat layer provides a glossy finish and resistance to stone damage. The system enables a single-coat application process that eliminates the need for a separate primer coat, reducing material and labor costs while maintaining performance characteristics.

CN105838199A-patent-drawing

20. Multi-Layer Paint Film with Single-Layer Basecoat Comprising Water-Soluble Polyurethane, Titanium Oxide, and Polybasic Glycol

2016

A multi-layer paint film for automotive applications that enhances durability through a novel basecoat formulation. The film comprises a basecoat comprising a water-soluble or water-dispersible polyurethane resin, titanium oxide, and a polybasic glycol, with a clear coating. The basecoat is applied in a single liquid layer, followed by a second basecoat without drying, and then a clear layer. This process eliminates the need for separate drying steps between basecoat applications, resulting in improved paint film performance. The basecoat formulation incorporates a water-soluble or water-dispersible polyurethane resin that has been optimized for automotive applications, while the titanium oxide enhances the paint's resistance to impact and abrasion.

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