776-00301 TYRIN IM bro - The Dow Chemical Company

TYRIN CPE in Pipes
The vast majority of PVC pipes is unmodified
and goes into applications where no particular
impact strength is required, such as
sewage pipes.
There are special applications which are
more demanding where impact modifiers can
be beneficial, such as:
• Pressure pipes for mining
• Gas pipes
• Special drain pipes (corrugated pipes)
• Pipes for wells or mining
• Foam core pipes.
Table 5: Starting point formulation
for HI PVC pipe
S-PVC K-68 100 phr
TYRIN 6000 6-8
3 basic lead sulphate 0.8
2 basic lead stearate 0.8
Ca-stearate 0.1-0.2
Stearic acid 0.2-0.3
CaCO3 5
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Typically, the impact strength requirements
are less demanding than for profiles. TYRIN
is the ideal product for pipe applications,
especially regarding the new or coming
European standards for pressure and nonpressure
pipes, where an impact test at 0°C
or even at -10°C will be required. TYRIN
reduces the transition temperature, giving
the end-users an extra margin of excellence
through low temperature impact performance
and ductility. TYRIN CPE modification also
yields a better surface which is useful to avoid
build-up on the inside of the pipe. This effect
is visible at very low levels and already 3-4
phr TYRIN 6000 are sufficient to give ductile
failure below 0°C.
TYRIN CPE offers excellent hot melt tear
strength, ductility, and welding properties,
essential in the extrusion of thin-wall
corrugated pipes. For foam core pipes, TYRIN
CPE can be used in both the compact and the
foam layer. In the compact layer, it improves
the ductility and in the foam section, it can
substitute to some extent the acrylic processing
aids which are used to improve the cell
structure. It will permit cost saving, improvements
of flammability, and a higher ductility
regarding impact tests at low temperature.
TYRIN CPE provides a consistent improvement
of the ductility of PVC pressure pipes and it
is possible to reduce the design coefficient,
where standardization and requirements
allow it. In practice this will yield a substantial
reduction of wall thickness which will
more than compensate for the slightly higher
cost of the impact modified compound. This
concept is not included in the current European
pipe standards.
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