DA 3303 E hostanox P-EPQ 09.07 RZ

Pigments & Additives Division
Plastic Business
Hostanox ®* P-EPQ ®
Clarifier Effect in Polypropylene
Exactly your chemistry.

Hostanox ® * P-EPQ ®
Introduction
Hostanox ® * P-EPQ ® is a highly
effective processing and color
stabilizer for thermoplastic polymers.
It is particularly recommended for
use in polyolefins, especially if tough
requirements, such as high temperature
or demanding shear conditions,
severely attack polymer melts during
processing.
One unique effect of Hostanox P-EPQ
is its contribution to improved transparency
of polyolefins. This additional
benefit of the processing stabilizer is
clearly pronounced in polypropylene
homo- and copolymers and in LLDPE.
2
> Clarifier Effect in Polypropylene
The classic nucleating agents, e.g.
benzoates, phosphates or sorbitol
derivatives, are typically intended to
influence the spherulite size distribution
and the morphology of semicrystalline
polymers. Characteristic
effects on the physical properties
are, for example:
> Increased crystallization
temperature
> Increased rate of crystallization
> Increased degree of crystallinity
> Reduced average size of the
spherulites
> Increased contact and/or seethrough
clarity
> Improved surface gloss
> Enhanced dimensional stability
of molded parts
> Improved mechanical properties,
such as tensile strength or flexural
modulus
Hostanox P-EPQ
Hostanox P-EPQ complements many
applications of nucleating agents
and may even compensate certain
draw-backs. Such combinations offer
additional benefits:
> Improved color retention during
melt processing
> Minimized yellowing of formulations
containing sorbitol derivatives
> Full compatibility with nucleating
agents
Some examples on the aspects
mentioned above are illustrated in
the following two chapters. All tests
were performed in third generation
polypropylene random copolymers.

Nucleating Properties of
Hostanox P-EPQ
Figure 1 illustrates the clarifying effect
of Hostanox ® * P-EPQ ® measured
on injection molded polypropylene
plaques. After the addition of 0.1%
Hostanox P-EPQ, the haze is reduced
by 10 - 15 % compared to the control
sample, whereas P-2 and P-4 have
significantly weaker effects. This
clarity improvement remains nearly
unchanged during multiple extrusion
at 270 °C. Typical clarifiers like NA-1
can even lose their performance under
severe stress conditions (e.g. peak
temperatures, prolonged heat exposure
of the melt), eventually yielding
only marginally improved haze values
in the finished plastic articles.
The improved transparency achieved
just by addition of Hostanox P-EPQ
correlates with an increase of the
tensile strength (TS) and the crystallization
onset temperature (COT).
As shown in Figure 2, Hostanox P-EPQ
can improve the tensile strength by
approx. 10 % compared to the reference
(BS only), whereas the competitive
stabilizers have less effect on this
property. The processing stabilizer
Hostanox P-EPQ can act to a certain
extent as a nucleating agent. It can
improve the clarity of polypropylene
and enhance its mechanical properties.
Haze (%) after ...
50
40
30
20
10
0
BS only P-EPQ P-2
P-4
BS + NA-1
Procedure: Multiple Extrusion at 270 °C.
Specimens: 1 mm Injection Molded Plaques.
Figure 1: Haze of Polypropylene Plaques
1st Extrusion 3rd Extrusion 5th Extrusion
Additives: BS: 0.05 % AO-2 + 0.1 % CaSt;
0.1 % Processing Stabilizer each;
0.25 % Nucleating Agent NA-1.
Tensile Strength
(N/mm
30
150
2 ) TS COT
COT (°C)
20
10
0
BS only P-EPQ P-2
P-4 BS + NA-1
Procedure: Mechanical Testing and DSC
Performed after one Extrusion Pass
at 270 °C.
Specimens: 1 mm Injection Molded Plaques.
Additives: BS: 0.05 % AO-2 + 0.1 % CaSt;
0.1 % Processing Stabilizer each;
0.25 % Nucleating Agent NA-1.
Figure 2: Crystallization Onset Temperature (COT) and Tensile Strength (TS) of Polypropylene Random Copolymer
100
50
0
3

Influence of NA-1 on the
Stabilization of Polypropylene
during Extrusion
Data on the melt and color stability of
polypropylene are shown in Figures 3
and 4, illustrating the effect of the nucleating
agent NA-1 on the performance
of the stabilizers Hostanox ® *
P-EPQ ® , P-2 and P-4 respectively. By
using 0.1 % Hostanox P-EPQ, optimal
melt stability is achieved for five repeated
extrusions. Its effectiveness
as melt stabilizer is almost maintained
also in presence of NA-1.
The corresponding results for the
color stability shown in Figure 4
support, furthermore, the preferred
use of Hostanox P-EPQ also in
nucleated polypropylene. It is evidently
superior to the competitive
phosphites P-2 and P-4.
4
MFR (g/10 Min.)
at 230 °C, 5 kg
20
15
10
5
0
only BS+P-EPQ P-EPQ P-2
P-4
Procedure: Multiple Extrusion at 270 °C.
Figure 3: Melt Stabilization of Polypropylene
The distinct properties of nucleated
polyolefins are significantly dependent
on the chemical structure and the kind
of nucleating agent applied. The typical
heterogeneous nucleators, such as
Hostanox 4030 or NA-3, are high
melting, salt-like compounds which
are primarily designed to improve
crystallization kinetics and mechanical
properties of a polymer. In contrast to
this, dibenzylidene sorbitols like NA-1
and NA-2 are preferably used as
clarifiers, i.e. for reduction of haze.
1 Pass 3 Passes 5 Passes
Additives: BS: 0.05 % AO-2 + 0.1 % CaSt;
0.1 % Processing Stabilizer each;
0.25 % Nucleating Agent NA-1 each.
Figure 5 shows the influence of
processing stabilizers on the haze of
polypropylene containing different
nucleating agents.
The formulations with NA-1 and NA-2
in Figure 5 are examples for highly
clarified polypropylene. In such cases,
processing stabilizers contribute only
marginally to further improvement of
the optical properties. However, if
heterogeneous nucleators are used
(Hostanox 4030 and NA-3 in Figure 5),
the generally higher haze values can
be clearly reduced in combinations
with Hostanox P-EPQ.

Yellowness Index
(on Plaques)
5
4
3
2
1
0
only BS+P-EPQ P-EPQ P-2
P-4
Procedure: Multiple Extrusion at 270 °C. Additives: BS: 0.05 % AO-2 + 0.1 % CaSt;
0.1 % Processing Stabilizer each;
0.25 % Nucleating Agent NA-1.
Figure 4: Color Stabilization of Polypropylene
Haze (%)
60
50
40
30
20
10
0
1 Pass 3 Passes 5 Passes
only BS 0.1 % P-EPQ 0.1 % P-2 0.1 % P-4
NA-1 NA-2 Hostanox ® *-4030 ®
Procedure: Haze measured after one
Extrusion Passage.
Specimens: 1 mm Injection Molded Plaques.
Figure 5: Effect of Processing Stabilizers in Nucleated Polypropylene
NA-3
Additives: BS: 0.05 % AO-2 + 0.1 % CaSt;
0.25 % Nucleating Agent each.
5

Conclusion
Hostanox ® * P-EPQ ® has to be considered
as the additive of choice in
applications of polypropylene where
superior stabilization is required.
Particularly in clarified or nucleated
polypropylene, the use of Hostanox
P-EPQ safeguards excellent melt and
color stability during processing of
the resin.
6
Experimental
Third-generation polypropylene random
copolymer was melt compounded
with the respective additive formulations.
The following base stabilization
(BS) was used: 0.1 % calcium
stearate plus 0.05 % AO-2. Processing
stabilizers (PS) were applied at 0.1 %
and nucleating agents (NA) at a level
of 0.25 %.
Preparation of the Samples
Additives were dry blended with the
polymer and pre-extruded at 210 °C.
Multiple extrusions were carried out
on a single screw laboratory extruder
(compression ratio 1:3, L:D = 25, 50
rpm). The strand was chilled in water
and pelletized. These samples were
used for MFR characterization, reprocessing
and for injection molding
into 100 x 100 x 1 mm3 plaques on
an Arburg Allrounder 221-75-350 at
245 °C.

Mode of Characterization
Melt Flow Ratio (MFR) according
to ASTM D-1238 (equivalent to ISO
1133) using pelletized polymer.
Yellowness Index (YI) according
to ASTM D-1925 measuring light
reflection on 1 mm plaques.
Haze Value according to ASTM D-1003
measuring light scattering through
1 mm plaques.
Tensile Strength (TS) according to DIN
53455 applying a crosshead speed of
10 cm/min. The specimens for tensile
testing were punched out of 1 mm
injection moulded plaques.
Crystallization Onset Temperature
(COT) measured on Mettler DSG.
Temperature (COT) 20 thermoanalyzer.
Starting temperature 200 °C, cooling
rate -10 °C/min.
Key to Abbreviations
AO-2:
Tetrakis-[methylene-3-(3',5'di-tert-butyl-4'-hydroxy-phenyl)propionate]-methane
P-2:
Tris(2,4-di-tert-butylphenyl)
phosphite
P-4:
Tris(nonylphenyl) phosphite
(TNPP)
Heterogeneous Nucleators
Hostanox ® * 4030:
Aluminium-monohydroxy-di-
(4-tert-butyl-benzoate)
NA-3:
Sodium-di-(4-tert-butyl-phenyl)
phosphate
Homogeneous Nucleators
NA-1:
1,3:2,4 Di-benzylidene sorbitol (DBS)
NA-2:
1,3:2,4 Di-(4-methyl-benzylidene)
sorbitol
7

Please note
This information is based on our present state of knowledge and is intended to provide
general notes on our products and their uses. It should not therefore be construed
as guaranteeing specific properties of the products described or their suitability for
a particular application. Any existing industrial property rights must be observed.
The quality of our products is guaranteed under our General Conditions of Sale.
® = Trademark of Clariant registered in numerous countries
®* = Trademark registered in numerous countries and licensed to Clariant
Edition: September 2007
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Clariant International Ltd.
Pigments & Additives Division
Marketing Plastic Business
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Phone: +41- 61- 469-7466
Fax: +41- 61- 469-7540
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Fax: +49 -821-479-2968
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Marketing Plastic Business
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Phone: +33 -389-89-6000
Fax: +33 -389-89-6197
Exactly your chemistry.
DA 3303 E_09/07