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Safety and Hygiene Precaution
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1 Safety
and Hygiene Precaution in Molding Operation
1.1 Precaution
in Molding
| Decomposition |
- Set the following material temperatures
and dwell time in the cylinder so as to avoid decomposing
materials.
- The appropriate material temperature
: 190 - 210

(Never heat up to 250
or higher)
- Dwell time in the cylinder
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Resin temperature
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Maximum dwell
time
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200
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60 min.
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210
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30 min.
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230
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10 min.
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- When molding is temporarily stopped, purge
the material from the cylinder and lower the cylinder temperature.
- If overheating is observed or suspected,
lower the cylinder temperature and purge the overheated
material by feeding a new material. In this case, gas emission
is restrained if the purged melt is immersed in water and
cooled.
When purging, wear protective glasses and gloves and do
not bring your hands and face close to the nozzle tip.
- Do not allow vinyl chloride resins or
halogen type fire retardants to mix with Duracon in the
cylinder, as they accelerate the thermal decomposition of
Duracon.
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| Gas |
- Partial or total ventilation in a molding shop is recommended
during molding operation.
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| Handling |
- Since pellets scattered on the floor may
cause operators to slip and fail, it is recommended that
they be removed at once by cleaning.
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1.2 Hygiene
Formaldehyde
gas is irritating, especially to the eyes and throat, and
inhaling the gas over a certain level of concentration for
a long period of time is dangerous.
For
this reason, partial or total ventilation is recommended during
operation.
Although
differences between individuals make it difficult to determine
the detection threshold of formaldehyde gas, it is thought
to be approximately 0.05 0.06
ppm.
The
maximum permissible quantity of formaldehyde recommended by
the Japan Society for Occupational Health is 0.5ppm per eight-hour
work shift, whereas the maximum permissible concentration
of formaldehyde provided in the U. S. is 0.75 ppm. |
1.3 Starting
Up, Shutting Down, and Changing of Materials
| 1.3.1 |
If the material previously
used was Duracon |
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Molding
can be started after the heater is turned on, the cylinder
temperature and nozzle temperature have reached the specified
level, and the cylinder is purged several times. In this
case it is necessary to confirm that the nozzle is open.
(This can be confirmed by checking for drooling from the
nozzle.)
When
stopping molding operations while the cylinder is being
filled with Duracon, stop resin feed, carry
out purging until no resin is discharged from the nozzle,
then turn the heater off.
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| 1.3.2 |
If the resin used in the
previous operation was not Duracon |
| (a) |
When the resin can be replaced
directly with Duracon |
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Resin
which can be molded within the same temperature range and
which has the same superior thermal stability as Duracon
- as polyethylene, polypropylene, polystyrene, and AS resin
- can be replaced directly by Duracon. |
| (b) |
When the resin must be
replaced with polyethylene or polystyrene and then with
Duracon |
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Resins
with higher molding temperatures such as polycarbonate,
nylon, PBT, PET, PPS or LCP, as well as resins such as polyvinyl
chloride, which have lower molding temperatures and could
decompose at molding temperature of Duracon,
cannot be replaced directly with Duracon. In
this case, the replacement procedure is as follows.
After
the cylinder is heated to the proper molding temperature
of the resin, the resin to be purged is replaced once with
polyethylene or polystyrene, and then polyethylene or polystyrene
is replaced in turn with Duracon after the
proper molding temperature for Duracon has
been reached. |
| (c) |
When the previous resin
is difficult to replace |
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If
the resin to be replaced has a dark color such as black
and the color cannot be easily replaced, it is recommended
that the cylinder be cleaned with a natural resin containing
glass fiber and then cleaned with a commercial cleaner.
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| 1.3.3 |
Replacement of Duracon
with another material |
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Replace
directly with the material if it has the same molding temperature
as Duracon.
However,
if the resin has a different molding temperature, replace
Duracon with polyethylene or polystyrene, then
change the temperature and replace with next molding material. |
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The data shown in this home page
are based on our accumulated experience and laboratory data, and
not always directly applicable to your products used under different
conditions. Therefore, we can not guarantee that the contents
of this home page are directly applicable as they are to the specific
condition in our customers, and we appreciate your final decision
on the use of these data.
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