lbs/cuft Density Semi-Rigid Structural Foam)
is one of our polyurethane foam formulations. It is closed-cell foam
with a good structural integrity and an enhanced skin quality.
Unlike polyurethane rigid foams, the physical properties of a cured
product have slight flexibility so it resists cracking and
chipping-off upon an impact. The application of this foam includes
backing structure for flexible concrete molds, various molded light
load-bearing parts, and other specialty applications.
Curing Agent (B)
Stoichiometry NCO/OH = 1.000/0.965
NCO Index: 1.036
Post Cure Oven:
100 -120°F (If needed)
may need to be heated to 100 – 120 °F if aluminum or steel mold is
10 - 15 seconds by hand batch
Pot life (pour within)
30 - 40 seconds
15 - 25 minutes with mold temperature 110 °F
Complete Cure Cycle:
1-2 days at room temperature
Recommended Processing (For Hand-Mixing Test):
recommend testing small amounts to see how the material actually
behaves, then develop your processing method accordingly. When you
process/test, please be sure to operate in a well-ventilated area or
large open area, wear rubber gloves, long sleeves, and protective
eyeglasses to avoid skin/eye contact. Read the enclosed Material
Safety Data Sheet for details on the safety and handling.
*Before you start your test, inspect both components A and B. In
winter, there is a chance the part-A material being frozen during
the transportation. If part-A has been frozen, you would see some
gel-like chunks in the material. In such case, you need to heat the
part-A component to 140 – 160 °F to thaw and agitate the content by
rolling the container. If you open the part-A container, be sure to
purge and blanket the material with dry nitrogen gas and shut the
air-tight lid. Do not use wooden paint stick as it has moisture
within, which to contaminate the material. After agitating the
component, keep the component in a room temperature above 70 ºF.
These materials will not freeze at room temperature. Do not storing
part-A component at a high temperature; this accelerates
deterioration of the quality. Part-B component is less likely to
freeze. However, under a very cold weather it may freeze and
separate. Part-B can be thawed by heating it to 140 -160 °F, or
leaving it at room temperature for a few days; agitate after part-B
are using an aluminum mold or steel mold, you may need to pre-heat
the mold and substrate to between 100 and 110 ºF. The material
creates heat from a chemical reaction. This heat is needed to cure
the material. If the material is directly in contact with a large
heat absorbing material, such as aluminum mold, steel mold, or
metal/stone object, this heat is taken away from the foam to cure.
Heating the mold too hot could lead to shrinkage of the foam after
it is cooled. Keep the temperature within 100 to 120 °F range if
auxiliary heat is needed.
mold release on the mold, if necessary. Do not use silicone-base
mold release as it destroys the foam surface.
correct ratio of part-A and part-B into a mixing cup. Mix well with
a steel or plastic stir stick for 20 to 30 seconds. Agitate
vigorously and thoroughly. Scrape the material off the side and
bottom of the cup as you mix. If you are using a hand-held power
tool for mixing, you should be sure to scrape the material off the
side and bottom of the mixing container to ensure thorough mixing.
life for this material is relatively short. There is a limit to how
much you can mix well by hands. Employing a meter mixing/casting
machine may be best for you production if your part is large or
requires a quantity to produce.
mixture into the mold. (See the following section for compression
foam in the mold for at least 15 to 20 minutes before demolding.
Please check the strength of the foam surface before demolding. The
foam is still soft and fragile at this point. Conduct your
evaluation test at least 24 hours after the mixing. The open top
surface may still be tacky at this point, but this normal. If you
have a thin section that is structurally weak, you may need to leave
it in the mold for a longer time.
room temperature for 24 hours to complete the cure cycle before
Because of closed cell structure, the foam will slightly shrink
after it is cured. The linear shrinkage should be less than 2%. If
you part requires tighter tolerance, you may need to modify your
mold to compensate the shrinkage.
the liquid mixture does not fill the mold, the foam needs to fill
the mold space with its expansion pressure. By slightly larger
amount of foam into a closed mold, you can obtain a better
resolution from the mold. The expansion pressure of the foam sends
the foam material to fill the mold to the expected shape.
The mold therefore needs to be close mold with a capacity to retain
the internal pressure. A simplest compression mold will be an
open-top box with a lid. The lid needs to be clamped by c-clamps or
furniture clamps to hold the pressure. The air trapped in the mold
could make large voids if it is not let out. For this purpose, you
need to have very small vent holes to let the trapped air escape
from the mold. You may need to actually try foaming the material to
see what parts of the mold have tendency to trap air; then create
vents to those places.
material can be metal, plastic, or elastomeric material. Mold
surface needs to be slick as foam could stick to any porous surface.
Metal molds tend to absorb the heat. Heat created from the urethane
reaction is required for foam to cure properly. If mold is cold,
this heat is absorbed and the foam does not cure properly. The mold
needs to be heat to 100 to 120 ºF in case of metal molds. If your
mold is made of a plastic or elastomeric material, such as silicone
rubber, epoxy, and urethane, this may not be necessary. Please test
and determine the optimal temperature for your mold. You may need to
machine off the small amount of material squeezing out from the vent
Compression rate is the rate in which how much more material you
would put in to create the pressure. Typically, about 10 %
compression should give enough pressure to distribute the foam
within the mold. This means you need to add 10% more of the material
than the volume free-risen foam would fill. Using higher rate makes
the foam denser and stronger.
see many small voids in the foam, this may be because the material
is cast in while the mixture is creaming and loosing its flow. If
creamed material is mechanically stirred, it may trap air and make
those bubbles. To prevent this, try casting the material within the
pot life or before the material is too thick.
In case the mold is thin and it is placed in a vertical position, if
the material touches the side wall of the mold and starts to
cream/foam from the side wall, this could create many small air
pockets as well. If the compression rate is high, these small voids
may be shrunk to invisible sizes. Try not to get the material on the
side wall when you are pouring the material in the mold. Changing
the position of the mold may help alleviating this problem.
Applications that requires fire-retardant property:
foam is not fire-retardant foam, and it is not recommended for
applications, which require or should be using fire-retardant grade
materials. The applications such as automotive interior, building
material, and components for some electronic parts often require
fire-retardant grade materials by law. It is the user's
responsibility to conform to the applicable regulations. We also do
not recommend this foam to be used to the applications in which the
foam can be exposed to high temperature or being near an ignition
adding fire retardant additives, this foam may be modified to
fire-retardant grade foam. The user must test the foam modified with
the fire retardant additives for the fire-retardant property and the
conformance to the applicable regulations.
component (prepolymer) contains isocyanate component, which is very
much sensitive to moisture. If it is left in air, part-A will react
with atmospheric moisture and will be ruined. This reaction is
non-reversible. Soon after opening a can and dispensing the content,
nitrogen gas or negative-40-degree-due-point dry air needs to be
injected to the can to blanket the material. Silica gel or calcium
chloride desiccant filter should be installed to 55 gallon drum-vent
for your drum feeding system. The storage temperature should be at a
room temperature between 65 and 90 ºF.
Part-B component may be hygroscopic. If the material is exposed to
ambient air, it may absorb moisture. Moisture contaminated part-B
material may become source of degradation or excessive bubbles in
the product. Avoid exposure of the material to air. Purging the
empty space in the container with nitrogen gas or
negative-40-degree-due-point dry air is also recommended to prevent
moisture contamination of part-B as well. The storage temperature
should be at a room temperature between 65 and 90 ºF.
component materials are industrial-grade chemicals. Please keep them
in a secure place and prevent access from any unauthorized
individual. The personnel who handle these materials need to read
the Material Safety Data Sheet (MSDS) for detail information on
safety and handling of the material. The MSDS for each component is
sent with the shipment of the material.
using this material, please be sure to operate in a wide-open area
with good air movement or in a well-ventilated area. Wear rubber
gloves, long sleeves, and protective eyeglasses to prevent skin/eye
contact of the material. When your operation involves heating or
spraying of the material, we recommend, in addition to the above,
installation of a proper ventilation system and using a half-face
respirator recommended for the use to prevent inhalation of the
Direct contact of polyurethane raw materials to skin/eye, as well as
ingestion may lead to health problems. No eating or smoking should
be permitted at the working area. The operator should wash hands
well with soap and water after handling the materials. Please refer
to the MSDS for each component for the detailed health information.
For any questions, please contact Northstar Polymers.
Notice: All of the statements,
recommendations, suggestions, and data concerning the subject
material are based on our laboratory results, and although we
believe the same to be reliable, we expressly do not represent,
warrant, or guarantee the accuracy, completeness, or reliability of
same, or the material or the results to be obtained from the use
thereof, neither do we warrant that any such use, either alone or in
combination with other materials, shall be free of the rightful
claim of any third party by way of INFRINGEMENT or the like, and
NORTHSTAR POLYMERS DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, OF
MERCHANTABILITY and FITNESS FOR A PARTICULAR PURPOSE.
Back to Foam Index
Back To Product Index
Back to Main Page