APPLICATION INFORMATION
ADDITIVES FOR PULTRUSION

TS-A 11

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Additives for pultrusion

Contents
03 Introduction

09 Processing additives

05 Process

10 Coupling agents

06 Raw materials

10 Additives with fiber wetting properties

07 Wetting and dispersing additives

11 Overview

08 Air release additives

03Introduction
Fiber-reinforced composites have shown remarkable growth in theautomotive, electrical, and construction industries since their introductionin the 1960s. They offer advantages over conventional materials such as
metal. They can achieve very high strengths and stiffnesses with a very low
weight. Furthermore, they are corrosion-resistant, have easily adjustableelectrical properties, high energy absorption, and low thermal conductivity.
Most important, however, is the individuality of each composite material.
This means that a fiber-reinforced composite can be optimally designed
for the requirements of the respective application by selecting suitablecomponents and sensible alignment of the reinforcing fibers.
Pultrusion is an automated process to produce fiber-reinforced plastic
profiles. In the continuous manufacturing process, a profile is createdthrough the targeted connection of fiber reinforcements and resin systems.
In pultrusion, additives are usually added to the resin matrix to optimize
the processing and properties of the product. Additives improve processcontrol and thus ensure lower process forces, higher production speeds,
and better product quality.
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 pultrusion

Examples for pultruded parts:• Transportation:
railway, train, tram, bus• Electrical industry• Construction, bridges• Wind energy

05

Additives for pultrusion

Process
Pultrusion is a continuous process for the production ofcomposites with constant cross sections and material
properties tailored to specific purposes with a consistentquality.

The fiber reinforcement impregnated with the resin systemis heated in a die and brought into the desired profile
shape. The profile is continuously pulled out of the die at
different speeds depending on the resin type and profile
cross-section, and cut to the required length.

The reinforcement is pulled through a guide and placed
precisely. The fibers are then processed through animpregnation area (resin bath or injection box), wherethe fibers are impregnated with the matrix material.

Pultrusion line
Fiber reinforcement

Continuous process

Guide plate

Resin bath or injection box

Heating and forming die

Pulling mechanism

Saw

G. 01

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Additives for pultrusion

Raw materials

Additives
Additives, despite their low dosage level, have a significant
impact on the properties of a composite and make theproducts economical. The following additives areparticularly interesting for pultrusion:

Resin systems
The resin system has the task ofdistributing the external forces evenly tothe embedded fibers. It also protects thefibers from environmental influences andcorrosion, and keeps the composite in its
shape.
In pultrusion, both thermosets andthermoplastics can be used as a matrix.
The difference between these lies mainlyin the form of curing. Thermosets arecured through a chemical crosslinking
reaction. The most common resins forpultrusion are unsaturated polyester resins
because they offer good properties at acomparatively low cost. Depending on
the application, vinyl ester, epoxy, acrylic,polyurethane, or phenolic resins are also
possible.

• Wetting and dispersing additives ensure a homogeneouscomposition in resin systems with fillers.
• Air release additives prevent and destroy air bubbles.
• Processing additives generally improve the handling of
the composite during processing.
• Coupling agents improve the fiber-matrix-adhesion andtherefore can increase mechanical properties.
Most of the additives can have a positive effect on fiber
wet-out.

Fillers
Various fillers are generally used to makeproduction as efficient as possible. Fillers
are inexpensive materials that are added tofill the volume and thus reduce material
costs. In addition, suitable fillers can also
improve the properties of the FRP. For
example, shrinkage is reduced, abrasion
resistance or flame retardancy is increased.

FibersFibers in composites absorb the highest possible forces. Flexuraland tensile strength as well as other important mechanicalproperties of fiber-reinforced plastics (FRP) are largely adjusted
by the embedded fibers. The simplest form of reinforcement
are unidirectional fiber bundles, so-called rovings. Further
possibilities are multiaxial nonwovens, fabrics, or fleeces, inwhich the anisotropy is largely compensated by means ofmultidirectional fibers. For the highest mechanical properties,
a combination of rovings and fabrics can be used.
The most commonly used reinforcement are glass fibers because
they provide a good cost-performance ratio with a moderatedensity.

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Additives for pultrusion

Wetting and dispersing additives
General use of wetting and dispersing additives

Anti-separation and anti-sedimentation additives

The use of wetting and dispersing additives can result in alower viscosity of the formulation. In addition, it is possible
to adjust the filler load while still maintaining the sameviscosity (G.02).

Anti-separation additives improve the homogeneity of theresin system and keep the system stable in the filled state.
BYK‘s anti-separation additives compatibilize the differencein the molecular weight of the components and improvecolor homogeneity and color depth of the compound.
To avoid sedimentation of fillers, special W&D additives
can be used to stabilize the solid particles.

Application example for wetting and dispersing additives
Viscosity
Increasing the filler load while
maintaining the viscosity

Reduction of viscosity

Filler loadWithout additive  

Formulation including wetting and dispersing additive

G. 02

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Additives for pultrusion

Air release additives
Air bubbles can develop into pinholes, which increases
porosity and dramatically reduces the overall performanceof the final part. BYK’s air release additives or defoamers
prevent and destroy these air bubbles and enable improved
processing, a perfect surface, and optimum productproperties.Air release additives work in three steps (G.03).

Step 2: Substances which stabilize the air bubbles are
displaced by the air release additive. As a result, smaller
bubbles coalesce to form larger bubbles, and the larger
bubbles rise to the surface faster because of their higher
buoyancy (Stoke’s law).
Step 3: Air bubbles break when they reach the surface.

Step 1: By reducing the interfacial tension between theresin and the solid particles (filler, pigments), the air fromthe particles is displaced into the resin solution.

Air release additives work in three steps
Step 1

Step 2

Step 1

Step 3

Step 2

Step 3G. 03

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Additives for pultrusion

Processing additives
Internal mold release agents or lubricants are used to reduce
friction in the die and to guarantee a continuous process.
BYK processing additives have generally positive influences
on a wide range of processing parameters and theproperties of the final product compared to standard
internal release agents. Due to the liquid delivery form of
the additives, they are easier to incorporate into the resin
system (G.04).

Benefits of BYK processing additives

Releaseagent

Releaseagent

Colorhomogeneity

Monofunctional
standard
additive

Shrinkagedecrease

Anti-separation
properties

Gloss
increase

Multifunctional
processing
additive

Haze
reduction

Perfect surface
appearance

G. 04

10Additives for pultrusion

Coupling agents
In pultrusion systems, the condition of interfaces is asignificant influencing variable for the efficiency in the final
application. Interfaces are developed where solids and liquids
or different solid structures meet. A multitude of molecularand physical forces determine how strong the bond isbetween these phases. The objective of coupling agents isto create as many stable additional bonds between the liquid
and the solid components to improve the mechanicalproperties. Coupling agents can improve both the staticand the dynamic resilience of the component throughimproved filler/fiber-matrix bonding (G.05).

The coupling effectNo coupling effectCoupling effect

Adhesive failure

Cohesive failure in the matrix
G.05

Additives with fiber
wetting properties

Improved fiber impregnation
Without additive

With additive

Additives with fiber wetting properties are used to optimize
the wetting process of resin systems on different fibers.
An enhanced wet-out of the fibers leads to a better qualityof the final part. By using these additives, an improved fiber
impregnation with no dry spots and no air entrapment canbe achieved (G.06).

G.06

11Additives for pultrusion

Overview
The following overview provides the products needed in your formulation to produce improved pultruded parts:
Application

Unsaturated polyester and vinylester

Acrylate

Epoxy

Polyurethane

Viscosity reduction and/or
increased filler load

BYK-W 908
BYK-W 985
BYK-W 996
BYK-W 9010
BYK-W 9011
BYK-W 9012

BYK-W 996
BYK-W 9010
BYK-W 9011
BYK-W 9012

BYK-W 985
BYK-W 996
BYK-W 9010
BYK-W 9011
BYK-W 9012
DISPERBYK-2152

BYK-W 903
BYK-W 969
BYK-W 996
BYK-W 9010

Pigmentation

BYK-9076
DISPERBYK-2152
DISPERBYK-2157

BYK-9076

BYK-9076

BYK-9076

Anti-separation

BYK-9076
BYK-W 972
BYK-W 974

RHEOBYK-D 410

RHEOBYK-7410 ET
RHEOBYK-D 410

BYK-P 9904
RHEOBYK-D 410

Anti-sedimentation

ANTI-TERRA-204
BYK-W 940
BYK-W 980
RHEOBYK-7410 ET
RHEOBYK-D 410

ANTI-TERRA-204
BYK-W 940
BYK-W 980
RHEOBYK-7410 ET
RHEOBYK-D 410

ANTI-TERRA-204
BYK-W 980
RHEOBYK-7410 ET
RHEOBYK-D 410

BYK-W 961
RHEOBYK-D 410

Air-release

BYK-A 515
BYK-A 555
BYK-A 560

BYK-070
BYK-A 515
BYK-A 555
BYK-A 560

BYK-1788
BYK-A 530
BYK-A 560
BYK-P 9920
BYK-S 732

BYK-054
BYK-088
BYK-A 535

Fiber wetting

Glass fiber:
BYK-A 515
BYK-A 560
BYK-W 972

Glass fiber:
BYK-A 515
BYK-A 560
BYK-W 972

Glass fiber:
BYK-A 525
BYK-P 9920
BYK-S 732

Glass fiber:
BYK-A 560
BYK-S 732

Carbon fiber:
BYK-9076

Carbon fiber:
BYK-9076

Carbon fiber:
BYK-9076
BYK-P 9920

Carbon fiber:
BYK-9076

Processing

BYK-P 9051
BYK-P 9065
BYK-P 9080

BYK-P 9051
BYK-P 9065
BYK-P 9080

BYK-P 9065
BYK-P 9912

BYK-P 9912

Mechanical properties

Glass fiber:
BYK-C 8000
BYK-C 8003

Glass fiber:
BYK-C 8000
BYK-C 8002

Glass fiber:
BYK-C 8001Carbon fiber:
BYK-C 8013
BYK-C 8014

For additional information
on additives from bio-basedmaterials, please refer tobrochure B-G 5:
Additives from bio-basedmaterials

Carbon fiber:
BYK-C 8014
T. 01

03/2022
TS-A 11BYK-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 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 infringingintellectual property rights of third parties. We reserve the right to make any changes according to technological progress or further developments.
This issue replaces all previous versions.