APPLICATION INFORMATION
ADDITIVES FOR EPOXY APPLICATIONS

TS-A 3

02

Additives for epoxy applications

Contents
03 Introduction to epoxy applications
04 Air release
06 Wetting and dispersing
08 Rheology
11 Surface additives
12 Coupling agents
14 Processing additives
19 Additive recommendations for epoxy applications

03

Introduction to epoxy applications
Epoxy resins are used today in a wide variety of different
products. This is attributed to good commercial availabilityof raw materials and also because of specific properties
such as:• Excellent electrical insulating values• Outstanding adhesion• Excellent chemical resistance• Good mechanical properties

These properties can be modified depending on the typeof resin and hardener system that is chosen and evenfurther influenced by the choice of other raw materials
used, such as fillers, reinforcements, and additives.
The selections made lead to reinforced products, such as
wind blades, pipes, automotive parts, and sporting goods(ski, surfboards, etc.), or to non-reinforced applications,such as flooring, mineral cast, putties, paints, adhesives,
and resins for electrical casting and insulation.
Along with this broad range of final applications comesa variety of different application techniques:
Reinforced parts could be made by simple manual lay-up,
but also by RTM or infusion technology, and several
casting or spraying technologies are available for nonreinforced systems.

For additional information
on additives and technical
topics, please contact us:
Thermosets.BYK@altana.com

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

04

Additives for epoxy applications

Air release
Entrapped air bubbles are a common challenge inmanufacturing or applying epoxy based systems. They
are difficult to remove, especially in highly thixotropic andpseudoplastic formulations or high wet film thickness.
These same air bubbles ultimately develop into pinholes,
which increases porosity and dramatically reduces the overall
performance of the final part. Defoamers as well as air
release additives can prevent:• Blisters in gelcoats• Pinholes• Loss of insulation properties in electrical casting systems• Weakening of the composite structure• Poor appearance• Porosityof the final part.

The additive is added to the resin or the hardener at the
beginning of the manufacturing or mixing process. Thisguarantees that it is active during the production of eachcomponent as well as during the mixing process of theresin and hardener prior to the application.

Air release in a solvent-free,
2-pack epoxy casting system
Without additive

With 1 % BYK-A 530

G. 01

Air release additives work in three steps
Step 1

Step 2

Step 1

Step 3

Step 2

Step 3G. 02

05

Additives for epoxy applications / Air release

Defoamers and air release additives can be based on(modified) polysiloxanes, silicon-free polymers, or a
combination of both. Whether or not a particular polymer
can destroy foam bubbles depends on the productcompatibility and solubility in the liquid medium. All
defoamers and air release additives must have some degreeof incompatibility – managing that delicate balance between
compatibility and incompatibility. This is achieved byadjusting the molecular weight and/or polarity of thepolymeric structures.
Some additives are especially designed for specificrequirements, e.g. potable water, FDA, AgBB, PIM, highvoltage, clear, etc. As regulations can change, please referto the relevant documents on our webside or contact our
product safety department.

Air release performance after the production process
Control
Additives to prevent air entrapment, foam, and pinholes

0 min.

1 min.

2 min.

3 min.

4 min.

5 min.

6 min.

7 min.

8 min.

9 min.

10 min. 11 min.

12 min.

13 min.

14 min.

15 min.

SystemProduct

Remarks

Silicone-based

BYK-077

Very effective, universal

BYK-A 525

Universal

BYK-S 732

Solvent-free, universal

BYK-1788

VOC-freeBYK-1790

Solvent free, for foodcontact applications(PIM)

BYK-A 501

Universal

BYK-A 530

Best air release effect inepoxies

BYK-P 9920

VOC-free, fiber wetting
performance

Silicone-free,polymer-based*

Silicone/polymer
combination

0.3 % BYK-1788* F or incorporation into the amine component, silicone-free
products are recommended.
G. 03

T. 01

06

Additives for epoxy applications

Wetting and dispersing
One of the most important steps in producing filled or
pigmented epoxy systems is the homogeneous distribution of
the solid pigments and filler within the liquid resin solution.
If this step (grinding) is not optimized, a wide range of
defects such as flocculation, flooding and floating (pigment
separation), and settling can occur as well as poor flow
behavior during application.

Wetting and dispersing additives are added prior to theincorporation of the filler/pigment. They will accelerate thewetting of solid particles, stabilize them, and can provide
the following benefits:• Viscosity reduction• Improved flow
• Increased filler load
• Reduced filler sedimentation• Color homogeneity

By using wetting and dispersing additives, a lower viscosity
can be obtained. When the viscosity is reduced, the choice
between better flow or an increase of filler load can bemade (G. 04).
Selecting the correct additive is dependent on theapplication requirements and the raw materials. Different
types of fillers require different wetting and dispersing
additives (G. 06 and G. 07). A combination of wetting anddispersing additives with air release additives will improve
the final result.

Better flow with BYK-W 985 in a mineralcasting filled with quartz

Wetting and dispersing additive: lower viscosity or higher filler load
Viscosity

Without additive

2 % BYK-W 985 on resin

Increasing the filler load while
maintaining the viscosity

Reduction of viscosity

d = 18.0 cm

d = 20.5 cm

Filler loadReference  

Formulation including wetting and dispersing additive

G. 04

G. 05

07

Additives for epoxy applications / Wetting and dispersing

Viscosity (Pa·s)

Viscosity reduction with quartz

Recommendations regarding viscosity reduction depending on filler type

40
35
30
25
20
15
10

Filler type

Product

QuartzBYK-W 985
DISPERBYK-2151

Calcium carbonate

BYK-W 996
BYK-W 985

Ammoniumpolyphospate

BYK-W 903
BYK-W 996

Aluminium hydroxide

DISPERBYK-142
BYK-W 903

Bariumsulfate

BYK-W 985
BYK-W 996

50Control

BYK-W 996

DISPERBYK-2151

Additive dosage: 1 % on filler

BYK-W 985
G. 06
First recommendation  

Viscosity (Pa·s)

Viscosity reduction with aluminum hydroxide

T. 02

Second recommendation

Recommendations for wetting and dispersing additives
Application

Product

Remarks

Strong viscosity reduction

BYK-W 903

Very effective with APP, suitable for anhydride
systems

BYK-W 985

Very effective, universal

60

BYK-W 996

Very effective with CaCO340

DISPERBYK-142

Very effective with ATH

Viscosity reduction
combined with anti-settlingproperties

BYK-W 980

Very effective, universal

Pigment stabilization andviscosity reduction

BYK-9076

Very stable in epoxy resin even at higher dosage

160
140
120
100
80

20
0
Control
Additive dosage: 1 % on filler

BYK-W 996

BYK-W 903

DISPERBYK-142
G. 07

DISPERBYK-2151
DISPERBYK-2152

Silicone/polymer
combination

ANTI-TERRA-204*

Suitable for amine hardener

BYK-W 940

Universal* Additives with higher amine values, like ANTI-TERRA-204, can cause viscosity increase whenused in epoxy part

T. 03

08

Additives for epoxy applications

Rheology
Rheology is impacting many properties of epoxy resin
systems, e.g. flow behavior, air release or sagging and settlingissues. Furthermore, the rheological profile of epoxy systems
is considerably affected after mixing resin with hardner due
to the mixing ratio and polarities of the components. It istherefore very important to formulate the rheological profile
of single components as well as the final system. To adjustrheology, BYK offers different types of rheological additives:• Liquid rheology additives• Solid rheology additives• Thixotropy booster

RHEOBYK-7410 ET is a modified urea that forms strong,
three-dimensional network structures, thereby creating
thixotropy.

All of them modify the sagging and/or settling properties.
Higher viscosity at low shear in combination with a highyield point can substantially reduce both sedimentation andsagging. This results in a longer shelf life with less settlingand better sag resistance during application.

Solid thixotrope additives are mainly used for anti-settling.
They build up a network between the single particles, andare easy to incorporate.

During storage, pigments and ﬁllers in a system can settle
and form sediments that are difficult to re-disperse. Thisdepends on the filler load, type of filler, and the storage
conditions (e.g. temperature).
During application on inclined and vertical surfaces, runningand sagging frequently occur at higher film thicknesses.

Liquid rheology additive
Liquid rheology additives are self-sufficient. They are used toadjust anti-settling and anti-sagging properties. They can be
added to the epoxy resin as well as to the hardener.
Examples for this additive family are RHEOBYK-7410 ET and
RHEOBYK-430.

RHEOBYK-430 is based on polyamides modified withcompatibility-enhancing groups (alkyl and polyether
segments) to optimize the incorporation as well as therheological activity. It creates a pseudoplastic flow behavior.

Solid rheology additives

In the correct combination with a thixotropy booster (e.g.
RHEOBYK-R 605, RHEOBYK-R 607), they also show an
excellent sag resistance.
GARAMITE-1958 and GARAMITE-7305 are solid thixotropes
based on the Mixed Mineral Technology (MMT), and can beeasily incorporated into in epoxy resins as well as into epoxy
hardeners.

Settling

Sagging

09

Additives for epoxy applications / Rheology

Thixotropy booster
Optimum processability coupled with high sag resistancerequires a perfectly adjusted rheology profile, and often
mixed minerals or fumed silica are used for this. However,if the amine hardener is added to the epoxy resin withthe solid thixotropes, the viscosity spontaneously drops.
A combination of modified solid thixotropes, especially
GARAMITE-7305, or hydrophilic fumed silica in the resin
and RHEOBYK-R 607 in the hardener can prevent this.

VCT – viscosity control technology
RHEOBYK-R 607 enhances the network of the solid
thixotrope and leads to a better sag resistance.

Viscosity Control Technology is a new processing technology
to achieve a special rheological profile of an epoxy system,
and is explained in the processing chapter.

An additional benefit can be found in reduced air
entrapments compared to hydrophobic fumed silica.

Higher sag resistance with RHEOBYK-R 607
and an additive based on mixed mineraltechnology (MMT)RHEOBYK-R 607 – mode of action

ControlWith additives

RHEOBYK-R 607
e.g. fumed
silica particle

Multiple functional groups effectively enhance the solid thixotropic network.

G. 08

G. 09

10

Additives for epoxy applications / Rheology

RHEOBYK-R 607 – less air entrapment
Hydrophobic FS

Hydrophilic FS + RHEOBYK-R 607

Recommendations for rheology additives
Product type

Product

Remarks

Liquid rheology
additives

RHEOBYK-7410 ET

Anti-sagging, anti-settling

RHEOBYK-410

Solid thixotropes

Thixotropy booster*

G. 10

RHEOBYK-430

Anti-settling, suitable for anhydride systems

GARAMITE-7305

Anti-sagging, anti-settling, combination withBYK-R 607 required

GARAMITE-1958

Anti-settling

RHEOBYK-R 605

Anti-settling for epoxy resin

RHEOBYK-R 607

Anti-sagging, anti-settling; to be added only to theamine component* In combination with fumed silica or additives based on MMT

T. 04

11

Additives for epoxy applications

Surface additives
Whenever an epoxy system is applied in a certain layer ona substrate, defects such as craters, Bénard cells, pinholes,
orange peel, and others can appear on the surface.
One very significant parameter that has an impact on allthese defects is the surface tension, or more specifically,
the surface tension differences. The following additives
could be used to prevent or minimize these differencesin surface tension.

Surface additives
SystemProduct

Remarks

Modified polysiloxane

BYK-306

Strong surface tension reduction; anti-cratering

BYK-310

Acrylate copolymer

BYK-A 525

Low surface tension reduction

BYK-361 N

Improved leveling

BYK-S 706

Easy-to-clean

Silicone acrylate copolymer

BYK-3550

Improved leveling and substrate wetting

Depending on the application field of the epoxy system,
it could be that it becomes exposed to a variety ofcontaminants such as dust and grease, and needs tobe fast, easy, and inexpensive to clean so as to savemaintenance costs.
BYK has developed a silicone-containing surface additive
specifically to improve cleanability (easy-to-clean effect).
BYK-SILCLEAN 3701 is a liquid product with 100 % active
substances. The additive achieves a permanent effect as
it reacts with the polymer matrix and, as such, does not
lose its effectiveness over time, like other silicone-based
surface additives.

T. 05

BYK-SILCLEAN 3701 – better cleanability
regardless of the contamination

Cratering and poor leveling

Without additive

G. 11

BYK-SILCLEAN 3701

Test system: conventional epoxy resin coating
Dosage: 1 % additive on total formulation
Contamination with carbon black

G. 12

12

Additives for epoxy applications

Coupling agents
Coupling additives are used wherever strength needs to be
increased or the structural degree of freedom enhanced.
Adhesion promoters are required when adhesion to a
substrate needs to be improved.
Coupling additives improve both the static and the dynamic
resilience of the component through improved filler/fibermatrix bonding. The chemical composition of the additives

enables bonding to the fibers or fillers and simultaneously
to the resin matrix. This unique characteristic allows forchanges in the component design and the production of
more resilient components. Another key benefit is a costsaving due to a targeted reduction in wall thickness, whilst
maintaining the necessary strength. Coupling agents are
typically applied in hand laminates, filament winding,pultrusion, and infusion applications.

BYK-C 8001 is a polymeric coupling agent and speciallydeveloped for use in reinforced epoxy resin systems. The
additive results in improved mechanical properties of thecomponent through increased filler/fiber-matrix bonding.
The additive is designed for glass fiber, non-treated glass
spheres or quartz filler. The extent of the improvement
depends on the choice of the glass fiber and epoxy resin
system.

Mode of action
Polymericresin-compatible group

Filler-active groups

Double bondWithout BYK-C 8001
Cohesive fracture

Adhesive fracture

Bonding

Resin

Silica sandFiller is usually only mechanically embedded in the resin. Under stress, filled parts break at the interface filler/resin. Coupling agents canstrengthen the interface between filler and resin by forming bonds, resulting in a remarkable improvement of mechanical properties.

G. 13

G. 14

Additives for epoxy applications / Coupling agentsThe use of the correct coupling additive in glass fiber
reinforced composites is necessary to maintain a highquality of the final part in terms of mechanical properties.
This is particularly true in structural parts like wind blades
or automotive components. Fiber sizings lose theirperformance over time depending on the storage
conditions, e.g. temperature, humidity, and therefore thequality of the final part is not guaranteed. By using acoupling agent, it is possible to regain mechanical properties
and maintain quality.

Improvement of mechanical properties with BYK-C 8001
Transverse tensile
strength (MPa)

13

60
50

+ 50 %+ 38 %

40
30
20

BYK-C 8001 either has to be added to the amine hardeneror can be incorporated during the mixing of amine hardenerand epoxy resin. The additive can be stored in standard
amine hardeners. The maximum storage time is affected by
the hardener composition and the additive dosage.

100
Controlresin 1
without additive

Resin 1
+ 1 % BYK-C 8001

Controlresin 2
without additive

Resin 2
+ 1 % BYK-C 8001

G. 15

Transverse tensile
strength (MPa)

Maintaining the performance of aged glass fibers with BYK-C 8001
60
50
40
30
20
10
0
0 dayscontrol

0 daysBYK-C 8001

1 week at 40 °C
control

1 week at 40 °C
BYK-C 8001

Storage conditions of glass fibers
G. 16

14

Additives for epoxy applications

Processing additives
Faster production cycles and new types of productionneed a new generation of additives with a couple offunctionalities to improve processing and quality aspects.

Interface chemistry is key for advanced composites

Faster cycle time and improved quality
Strength–
Coupling
technology

Processing additives are developed in order to reduce thecycle time and accelerate the RTM or HP-RTM process by
ensuring good demolding after curing in conjunction
with external release agents. The external mold releaseapplication frequency is prolonged. This results in an
improved potential output of the production process (G. 18).
BYK-P 9912 is a processing additive with internal releaseproperties for unfilled, filled, and fiber-reinforced systems.
This results in an improved potential output of the
production process with regard to a reduced downtime of
the mold. BYK-P 9912 has no negative impact on processing
parameters such as viscosity and reactivity. The final partprovides a ready-to-coat and ready-to-bond surface at thesame composite specification but with improved quality.

Processing
speed–
SurfacetechnologyLightweight–Processing
technology

Interface

High-quality
parts–
Processing
technology

Easierhandling–
Rheology
technology

G. 17

15

Additives for epoxy applications / Processing additives

Optimized production cycle

Production cycle with standard mold release agent
1. Cycle
External moldrelease

2. Cycle
Reinforcing
fibersInjection ofsystems

CuringDemoldingCleaning
moldExternal moldreissue

Reinforcing
fibers

Production cycle with BYK processing additives
1. Cycle
External moldrelease

2. Cycle
Reinforcing
fibersInjection ofsystems

CuringDemolding

Reinforcing
fibers

G. 18

16

Additives for epoxy applications / Processing additives

Improved wetting and faster processing
Processing additives are used to improve the wetting processof epoxy resin systems and different kinds of fiber in a
multitude of fiber-reinforced applications. Besides the
optimized fiber wetting, the additives reduce the processing
time.

Improved quality with better fiber wetting
Glass fiber
Without additive

BYK-P 9920

BYK-P 9920 is an emission-free wetting agent for fiberreinforced plastics with defoaming properties. The
combination leads to a faster processing and a higher
quality in the final compound. By using the additive, abetter fiber impregnation with no dry spots and no air
entrapment will be achieved.

G. 19

Resin transfer
molding (RTM)17

Additives for epoxy applications / Processing additives

Faster processing and cost saving with VCTViscosity Control Technology (VCT) is a new technology thatis based on a pair of well-engineered processing additives todesign the viscosity of 2-pack systems and their components
to an optimum level for every single process step. Thereis one processing additive (Thixbreaker) for the resin
system and a matching one for the hardener component(Thixbooster). The perfectly synchronized interaction of
the two processing additives that comes into effect when
the components are mixed together ensures that the final
application viscosity is exactly as required.

BYK-P 2710 (Thixbreaker) + BYK-P 2720 (Thixbooster) are
the processing additives of Viscosity Control Technology
for solvent-free and solvent-borne epoxy resins containinghydrophilic fumed silica for anti-sagging properties inmedium/high viscous systems. They are designed to achieve
low viscosity levels of thixotropic epoxy resin and amine
hardener components by gaining a high viscosity
immediately while mixing the resin and hardener for
application (G. 20).

Comparison between industry standard and the use of VCT technology
Today’s standard

Required application viscosity

New solution with VCTViscosity

High

Low
Component A• Epoxy resin• Hydrophobic FS

Component B• Amine hardener• Hydrophilic FS

Component A+ component B

Component A• Epoxy resin• BYK-P 2710
• Hydrophilic FS

Component B• Amine hardener• BYK-P 2720(• Hydrophilic FS)
G. 20

18

Additives for epoxy applications / Processing additives

The new formulation only needs hydrophilic fumed silica,
BYK-P 2710 (Thixbreaker, it blocks the structural build up of
the hydrophilic fumed silica) in the resin component, and
BYK-P 2720 (Thixbooster, it reanimates and enhances the
structural build-up of the hydrophilic fumed silica) in theamine hardener to achieve low viscosity during production(G. 21) but high application viscosity after mixing (G. 22).
The concept of Viscosity Control Technology has a highly
beneficial effect on the total value chain.

VCT optimizes cost, time, and quality in formulation,
production, transportation, and application, and provides
benefits in:Process + quality• Faster and improved incorporation of hydrophilic
fumed silica• Low viscous components are faster to process and to fill
• Less air entrapment and faster evacuation• Adjusted viscosities lead to a better mixing quality• Lower viscosities permit lower pressure and higher
output in the metering machine

Viscosity in production

Cost saving• Use of cheaper hydrophilic fumed silica insteadof hydrophobic fumed silica• New packaging and transportation opportunities• Shorter production time

Viscosity at application

G. 21

G. 22

19

Additives for epoxy applications

Additive recommendations for epoxy applications
Application

Air release

Viscosity
reduction

Flow/leveling, Anti-settling
anti-cratering

Rheology

Pigment
stabilization

Processing

Gel coats

BYK-A 530
BYK-1790

BYK-W 980

BYK-306
BYK-310
BYK-320GARAMITE-7305
RHEOBYK-R 607*²

DISPERBYK-2152
BYK-W 940

BYK-P 9912

Casting systems, BYK-A 501
polymer
BYK-A 530
concrete,
BYK-1790
mineral cast

BYK-W 985
BYK-W 996
BYK-W 980

Lay-up,spray-up

BYK-W 980
BYK-W 996

BYK-A 501
BYK-A 530
BYK-A 525

InfusionBYK-A 530
techniques, RTM BYK-1788

RHEOBYK-R 605*¹
RHEOBYK-410
RHEOBYK-7410 ET

Fiber wetting

Coupling

BYK-P 9920
BYK-9076

BYK-C 8001*³

Substrate
wetting

Viscosity control
technology (VCT)GARAMITE-7305
RHEOBYK-410
RHEOBYK-7410 ET
GARAMITE-1958
RHEOBYK-R 605*¹
RHEOBYK-R 607*²
BYK-310BYK-A 525

BYK-P 9912

Lining, flooring

BYK-A 501
BYK-A 530
BYK-1790

BYK-W 985
BYK-W 980

BYK-306

GARAMITE-7305
RHEOBYK-410
RHEOBYK-7410 ET
ANTI-TERRA-204
GARAMITE-1958

RHEOBYK-R 607*²

Electrical cast

BYK-A 530
BYK-S 732
BYK-1790

BYK-W 903
BYK-W 985

BYK-306

GARAMITE-7305
RHEOBYK-410
RHEOBYK-7410 ET
ANTI-TERRA-204
GARAMITE-1958

RHEOBYK-R 607*²

Bonding pastes

BYK-A 530
BYK-P 9920

BYK-W 985
BYK-W 903

RHEOBYK-410
RHEOBYK-7410 ET
GARAMITE-1958

BYK-P 2710*¹ (only
fumed silica)
BYK-P 2720*²

Chemicalanchors

BYK-A 530
BYK-P 9920

BYK-W 996
BYK-W 985

RHEOBYK-410
RHEOBYK-7410 ET
GARAMITE-1958

BYK-P 2710*¹ (only
fumed silica)
BYK-P 2720*²

First recommendation  

Second recommendation*¹ in combination with GARAMITE or fumed silica*² in combination with GARAMITE or fumed silica; only for amine component*³ only for amine component

BYK-307
BYK-392
BYK-361 N

T. 06

02/2022
TS-A 3
BYK-Chemie GmbH
P.O. Box 10 02 45
46462 Wesel
GermanyTel +49 281 670-0
Fax +49 281 65735

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info@byk.com
www.byk.com

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 to use. No warranties of any kind, either express or implied, including warranties of merchantability or fitness for a particular purpose, are maderegarding any products mentioned herein and data or information set forth, or that such products, data or information may be used without infringing
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