APPLICATION INFORMATION
ADDITIVES FOR ACRYLATE APPLICATIONS

TS-A 902

Additives for acrylate applications

Contents
03 Introduction to acrylate applications
05 Air release additives
06 Improvement of mechanical and chemical properties
07 Viscosity reduction
08 Anti-settling /anti-floating
09 Pigment stabilization
10 Acceleration of curing reaction
11 Suppression of MMA emission
12 Summary of additive recommendations

03

Introduction toacrylate applications
In this brochure, “acrylate applications” refers topolymethyl methacrylate (PMMA) solutions inmonomeric methyl methacrylate (MMA) thattypically contain about 20 % PMMA. This resin
solution (often called “syrup”) is mixed with fillers
such as ATH (aluminum trihydroxide) or quartz(silica sand) and then cured at ambient or elevatedtemperatures using a peroxide initiator. To achieve
special decorative effects, pigments (white orcolored) as well as different types of flakes are also
used in addition to the filler.
Different objects can be produced with acrylic syrup
such as high quality bathtubs, sinks, and othersanitary equipment. Slabs and plates are otherproducts with excellent abrasion resistance forvarious uses.

The right choice of additives can improve the acrylic
syrup processing and quality of the final parts inmany ways:• Reduced air entrapments•	Improved mechanical and chemical resistance•	Reduced syrup viscosity, allowing higher
filler loads•	Less settling and floating of filler, pigments,and flakes• Pigment stabilization, no flocculation•	Accelerated curing reaction and morehomogeneous curing•	Reduced monomeric methyl methacrylateemission

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 acrylate applications

Examples of typical acrylate applications

05

Additives for acrylate applications

Air release additives
Air is easily incorporated into the acrylic syrup during
mixing operations and while fillers and other solid particles(pigments, flakes) are being dispersed. If these air bubbles
are not completely removed from the system before
curing, such air entrapments will negatively affect theoptical and mechanical properties of the final parts.
A vacuum is often used for air release. Additives are very
helpful in accelerating this process and minimizing thetime necessary to remove the air.

Air release additives work in three steps. Step 1: By reducing
the interfacial tension between the acrylic syrup and the solid
particles (filler, pigments), the air from the particles isdisplaced into the resin solution. 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 larger bubbles rise to the surface fasterbecause of their higher buoyancy (Stoke’s law).
Step 3: Air bubbles break when they reach the surface.

Air release additives
ProductRecommended forDosage

BYK-390

All types of acrylicsystems

0.3 –1 % on syrup

BYK-1790

All types of acrylic
systems, especiallyfor food contact
applications*

0.3 –1 % on syrup

BYK-A 515

All types of acrylic
systems

0.3 –1 % on syrup* For the use in food contact applications pleasecheck the food contact sheet.

T. 01

Air release additives work in three steps
Step 1

Step 2

Step 3G. 01

06Additives for acrylate applications

Improvement of mechanical and chemical properties
Filler particles are usually only mechanically embedded in
the acrylic resin matrix, and filled parts typically break at
the filler/resin interface under mechanical stress. Coupling
agents strengthen the interface between the filler particles
and the acrylic resin by forming chemical bonds, which inturn significantly improves the mechanical and/or chemicalproperties.

Using these coupling agents, for example, can increase
flexural strength by a range of 10–50 %. Chemical andwater resistance is also significantly improved particularly
in quartz-filled systems. G. 03 shows the results of a hotwater immersion test.

Coupling agents
ProductRecommended forDosage

BYK-C 8000

Quartz and glass flakes

0.5 –1.5 % on syrup

BYK-C 8002

ATH

0.5 –1.5 % on syrup
T. 02

Mechanism of coupling agents

Hot water immersion test (200 h)
Polymeric resincompatible group

10 µm

Filler-active groups

Double bondwithout BYK-C 8000
10 µm

BondingResin

Fillerwith BYK-C 8000

G. 02

G. 03

07

Additives for acrylate applications

Viscosity reduction
The quantity of filler in a highly filled acrylic system should
be as high as possible, but at the same time, viscosity must
be low enough to guarantee problem-free handling andprocessing. Wetting and dispersing additives can be very
helpful to combine high filler loads with low viscosity.
These additives adsorb onto the filler surface and minimize
the interaction between the polar particles, which results ina much lower viscosity.

Wetting and dispersing additives for viscosity reduction
Product

Recommended forDosage

BYK-W 969

ATH, silane-treated silica sand

0.3 –1.5 % on syrup

BYK-W 980

Silica sand

0.3 –1.5 % on syrup
T. 03

Mechanism of viscosity reduction
Wetting anddispersing additives
reduce interactiveforces and create
lower viscosity

Viscosity reduction in an
ath-filled acrylic system
Viscosity (mPa·s)

Interaction of filler particles
leads to high viscosity

1400
1200
1000
800
600
400
Control

G. 04

BYK-W 980

Syrup: 20 % PMMA in MMA; Filler load: 60 % ATH
Additive dosage: 1 % based on filler

BYK-W 969

G. 05

08

Additives for acrylate applications

Anti-settling/anti-floating
In acrylic casting systems, viscosity should be low in order toobtain good flow in the mold. Consequently, many systems
face settling (sedimentation) or floating problems with thesolid particles (filler, flakes). Achieving good flow properties
while experiencing no settling or floating issues requires theuse of specially developed wetting and dispersing additives
or coupling agents that support such behavior.

Wetting and dispersing additives to prevent settling and floating
Product

Recommended forDosage

BYK-C 8002

ATH filled systems

0.3 –1 % on syrup

BYK-P 105

All types of acrylic systems0.3 –1 % on syrup
T. 04

These multifunctional additives adsorb onto the particle
surface and form bridges between several particles.
This network structure very effectively reduces settlingand floating.

Mechanism of multifunctional wetting and dispersing additive

Anti-floating

Floating
without
additive

G. 06

No floatingwith 0.3 %BYK-C 8002
(on filler)

G. 07

09

Additives for acrylate applications

Pigment stabilization
Many applications require pigmentation of the acrylic syrup
to achieve an optimum appearance. White pigments(titanium dioxide) are often used, but colored pigments(inorganic and organic) are also utilized for special
decorative effects. Pigments tend to agglomerate with eachother, with other pigments, or with the filler particles.
Such flocculation negatively affects color homogeneity,color shade, and hiding power.

Additives for pigment stabilization

Flocculation can be minimized by using appropriate wetting
and dispersing additives. These additives stabilize thedeflocculated particles and prevent reflocculation. A stableand uniform color effect is thus guaranteed.

Additive dosage strongly depends on the particle size ofthe pigments. Small particles with a larger specific surface
area require higher amounts of wetting and dispersing
additives than coarser particles with a smaller specificsurface area.

Product

Recommended forDosage

BYK-W 940

Fillers and inorganic pigments

1– 5 % on pigment/filler

DISPERPLAST-1142

All types of fillers and pigments

1–10 % on pigment/filler
T. 05

Pigment stabilization with wetting and dispersing additives

G. 08

10Additives for acrylate applications

Acceleration of curing reaction
Curing of the acrylic system can be accelerated withCa2+ ions. Dry Ca(OH)2 or a suspension of Ca(OH)2 inmethyl methacrylate (MMA) is usually added to the syrup/
filler mixture for that purpose, but both forms have theirdisadvantages:
Suspension of Ca(OH)2 in MMA:•	Difficult handling of dry Ca(OH)2 to produce thesuspension• Agglomeration and sedimentation of Ca(OH)2
Dry Ca(OH)2:• Difficult to handle (corrosive)• Difficult to dose materials in powder form
• No homogeneous distribution in the mixture•	Moisture and CO2 absorption leads to reactivity
change over time

Using Ca(OH)2, either in powder form or in suspension,presents handling difficulties and can also lead to aninconsistent curing situation. This may negatively impact
the quality of the final parts.
BYK-2616 is a CaO paste with 74 % CaO and is thebetter way to accelerate acrylic syrup curing:• Pumpable paste• Dust-free handling• Fine particles in a very homogeneous distribution• Fast acting due to large specific surface area
• Excellent storage stability
Overall, BYK-2616 facilitates accelerated curing that isconsistent and homogeneous and enables the productionof high-quality final parts.

Curing accelerator
ProductRecommended for

DosageBYK-2616

Ambient temperature
curing acrylic systems

0.5– 2 % on syrup
T. 06

11Additives for acrylate applications

Suppression of MMA emission
A typical acrylic syrup contains about 80 % monomeric
methyl methacrylate (MMA), which has a high vapor
pressure of 40 hPa and evaporates quite easily. Therefore,
a considerable amount of MMA can be detected in theworkplace when an acrylic syrup is exposed to air.

Emission suppressantsTo avoid the unpleasant smell of MMA and protect theworkers, the MMA emission should be as low as possible.
Emission suppressants such as BYK-S 782 can reduce theMMA emission substantially; a reduction of more than
80 % is possible.

ProductRecommended forDosage

BYK-S 782

All types of acrylicsystems

0.5 –1.5 % on syrup
T. 07

MMA Emission (g/m2)

MMA emission of a filled acrylic system

500
400
300
200
10000102030405060Time (min.)BYK-S 782 based on resin:  

0 %  

0.5 %  

Syrup: 20 % PMMA in MMA; Filler load: 60 % ATH

1 %  

1.5 %

G. 09

12Additives for acrylate applications

Summary of additive recommendations
Additive recommendations for acrylate applications
EffectProduct

Air release and defoaming

BYK-390
BYK-A 515
BYK-1790*

Improvement of mechanical and chemical properties

BYK-C 8000
BYK-C 8002

Viscosity reduction

BYK-W 969
BYK-W 980

Anti-settling and anti-floating

BYK-P 105
BYK-C 8002

Pigment stabilization

BYK-W 940
DISPERPLAST-1142

Acceleration of curing reaction

BYK-2616

Suppression of MMA emission

BYK-S 782

First recommendation  

Second recommendation* For the use in food contact applications please check the food contact sheet.

T. 08

12/2021
TS-A 9BYK-Chemie GmbHP.O. Box 10 02 4546462 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 infringing
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