Molding
Pre-drying
Modified PPE has the lowest moisture absorption of any engineering
plastic and displays excellent hydrolysis resistance. To help
ensure against surface appearance faults such as silver streaks,
it is nonetheless good practice to predry the material. For
applications where surface appearance is critical, always
be sure to predry the material. When using a PPE/PA grade,
predrying is especially important due to the high moisture
absorption properties of PA.
Predrying should be done at the proper temperature range specified
for each grade. A closed loop dehumidifying/drying hopper
system is the most efficient equipment for predrying Xyron.
When using hot-air circulating ovens, Xyron pellets will be
efficiently predried when spread out in trays at a uniform
depth of 20 to 30 mm.
Take care to ensure that Xyron is not predried for longer
than 8 hours. Excessive predrying may result in degradation
of physical properties and color changes.
Regrind
Properly molded Xyron (sprues, runners, molded articles, etc.)
may be reground, dried, and remolded without adverse effects.
It is essential that material to be reground be free from
oil, grease, dirt, and foreign substances, and shows no signs
of degradation. Regrind levels up to 20% can be used successfully,
but it is not advisable to use reground material for applications
where surface appearances are critical.
Purging
High viscosity GPPS and Asaclean SA™ (available from
Asahi Kasei Chemicals Corporation and distributors) are recommended
purging materials for all Xyron grades. Purging should be
performed at temperature ranges appropriate for each grade.
Downtime
In order to prevent polymer degradation when molding operation
is stopped or interrupted, the following measures are recommended.
- Up to 30 minutes:
Maintain cylinder temperature. Purge barrel using same material
prior to the re-start of molding operation.
- From 30 minutes to 12 hours:
Decrease cylinder temperature to 200-220°C. Purge
barrel using high viscosity GPPS. Upon commencement of molding
operation, Purge barrel using material for molding after
increasing cylinder temperature to the required level.
- For downtime longer than 12 hours:
Purge barrel with high viscosity GPPS, and shut down machine.
Mold release
Generally, mold release agents are not required for molding
Xyron resins. In cases where mold release agents are needed
due to the complex shape of the mold, minimal use is recommended.
Silicone-based mold release agents such as Pelicoat B™
(manufactured and sold by Chyukyo Kasei Kogyo Ltd.,
Japan) are recommended, as the chemical ingredients do not
react
with Xyron.
NOTE:
The information provided here is accurate to the best of our
knowledge, based on all information and data available at
this time, and is subject to change without notice. It is
provided with no guarantee or assumption of liability whatsoever.
It applies only to the normal handling and use of Xyron as
a molding material. Any other use or application would necessitate
additional, special safety precautions, and is not recommended.
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