TECHNICAL INFORMATION
ADDITIVES FOR ED COATINGS

L-TI 3

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Additives for ED coatings

Contents
03 Introduction
04	Application technology equipment at BYK: competence and customer orientation
05 Stabilization of ED baths
06 Improvement of anti-cratering properties
07 Leveling optimization
08 Defoaming
09 Improvement of adhesion and recoatability

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Introduction
ED (electrodeposition) coatings are used both in the automotive
industry and in the industrial sector. A distinction is made between
cathodic electrodeposition (CED), which is the most commonly used
process, and anodic electrodeposition (AED), which is used mainly in
the industrial sector.
The benefits of ED coatings lie in their short application time, uniform
layer thickness, good adhesion, corrosion and chemical resistance,and excellent cost-effectiveness resulting from high efficiency.
Furthermore, environmental compatibility is an aspect that is more
important than ever in today’s world.
Angled objects that have hollow spaces, like car bodies, are difficult
to reach properly and coat using conventional application methods
such as a paint gun. Using the principle of electrodeposition enables
the paint to reach all areas and therefore guarantee good corrosion
protection there too.

NoteTo ensure the best appearance
and full functionality, please
open in Adobe Acrobat.

Suggested additives for theED sector can be found at:www.byk.com/en/markets/
automotive-oem-coatings

However, the ED coating can only achieve all these benefits if theunderlying coating system is perfectly adapted and optimized to theapplication. Additives play a very important role here. BYK offers
solutions for a wide variety of applications in this regard:• Wetting and dispersing additives not only provide good pigment
stabilization and improved anti-settling performance, they also
have a positive effect on leveling.
• Surface additives not only improve leveling, they also make thesystem insensitive to contamination, avoid the formation of craters,and thus ensure good corrosion protection.
• Defoamers prevent foaming in the ED bath, thereby optimizing theapplication result and allowing a defect-free coating film to becreated.
Thanks to our specialized laboratories and the ability to simulate theED process under laboratory conditions, BYK is capable ofrecommending specific additives for customer systems and also
developing new additive solutions for the ED market.

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Additives for ED coatings

Application technology equipment at BYK: competence and customer orientation
Our laboratories in Germany, China, and Japan are equippedwith ED facilities that we use to simulate our customers’
different applications under laboratory conditions, test theeffect of our additives in the corresponding systems, andthus offer solutions for a wide range of problems.

The ED facility creates an electric field between the sheet
metal being coated and the opposite pole; an electrochemical
reaction takes place whereby the paint is coagulated anddeposited on the sheet metal as an insoluble film.
The combination of the ED bath and ultrafiltration allows
the paint to be applied professionally, as it would be in alarge-scale system, and the permeability of the products
can be checked during ultrafiltration too.

Our laboratory facilities consist of:
1. Rectifier
2. ED bath3. Ultrafiltration unit

Rectifier andED bathUltrafiltration
under laboratory
conditions

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Additives for ED coatings

Stabilization of ED baths
As in all coating systems, pigment stabilization is a key issuein ED coating too. Choosing the right additives not onlyensures stability of the ED bath, but also has a positiveeffect on properties such as leveling and appearance (gloss).
The effectiveness and compatibility of our additives can betested using different test methods such as the cup test,
L profile, and pour out on foil.

Selecting the right additive
Insufficiently stabilized ED bath leads to:• Poor leveling• Rough surface

Incompatibility leads to:• Poor leveling• Surface defects

Stabilized ED bath leads to:• Good leveling• Smooth surfaceG. 01

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Additives for ED coatings

Improvement of anti-cratering properties
In the industrial and automotive sectors, standard ED baths
can be more than three hundred cubic meters in volume.
Contamination of the ED bath can cause surface defects
such as cratering, which is a major problem because this not
only affects the appearance but also has a negative impact
on corrosion protection. Anti-cratering additives can help
minimize defects like these and reduce the ongoing quality
costs associated with them.

As well as by contamination of the ED bath, cratering canalso be caused by insufficient cleaning of the substrate oreven by the influence of oil vapors from the air in thebaking zone. These defects can likewise be prevented byusing suitable additives.
The “toothbrush test” or “aluminum cup test” can be used
to simulate the contamination described above and develop
suitable additive solutions.

Toothbrush test
Without additive

Aluminum cup test
With anti-cratering additive

Without additive

G. 02

With anti-cratering additive

G. 03

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Additives for ED coatings

Measurementwith thewave-scan

Leveling optimization
Good leveling is not only important for the visual appearanceof the ED coating; it also lays the foundation for all thesubsequent coating layers.
The wave-scan measuring device from BYK-Gardner enables
the waviness of the deposited coating to be checked, whichmakes it possible to judge the effectiveness of an additive.

Roughnessmeasurement

In addition to the wave-scan, the Hommel tester can beused to analyze the leveling and roughness, thus allowing
the right additive for the respective system to be selected.

Using a surface additive to improve roughness
Without additive: poor levelingWith surface additive: good levelingWith surface additive

Without additive

G. 04

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Additives for ED coatings

Defoaming
An ED formulation consists of approximately 80 % water.
The other components can have a foam-stabilizing effectsimilar to surfactants. This can not only cause problems in
the process sequence, but can also have a highly detrimental
effect on the quality of the coating and a negative impact
on its anti-corrosive properties, for example. It is therefore
important to avoid foam formation and stabilization in theED bath in an effective and lasting manner. In this regard,
BYK defoamers play a significant role in ensuring that theprocess is controlled and that the coatings are high quality.
The effectiveness of the additives can be tested using thestamping method, which assesses the formation andstability of the foam.
Stamping
method forfoam testing

Effect of different defoamers in the ultrafiltrate

G. 05

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Additives for ED coatings

Improvement of adhesion and recoatability
Good adhesion to the subsequent layer is essential for any
coating and therefore plays a key role. Adding special
additives can, for example, increase the surface energy ofthe coating layer and thereby improve the subsequentadhesion. This makes it possible to achieve improved stone
chip protection in the automotive sector or a more robust
surface coating in the industrial sector.

About BYKBYK additives offer a wide range ofapplications for ED coatings. They improve
product properties, optimize production
processes, and therefore ensure perfectapplications and the best possible property
profiles in the end use. BYK is yourtechnology partner for improving specificproperties of ED coatings in the automotive
industry and industrial sector.

Using an adhesion promoter to improve adhesion
Without additive

With additive

If you have any questions orrequire technical support,
please do not hesitate to contact
our global ED coating team at
ecoat.byk@altana.com. Suggested
additives for the ED sector canbe found at: www.byk.com/en/
markets/automotive-oem-coatings

G. 06

07/2022
L-TI 3
BYK-Chemie GmbH
Abelstraße 4546483 Wesel
GermanyTel +49 281 670-0
Fax +49 281 65735

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The information herein is based on our present knowledge and experience. The information merely describes the properties of our products but noguarantee of properties in the legal sense shall be implied. We recommend testing our products as to their suitability for your envisaged purpose prior touse. No warranties of any kind, either express or implied, including warranties of merchantability or fitness for a particular purpose, are made regarding
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This issue replaces all previous versions.