|
| Q-001 |
 |
What is a
one-component polyurethane foam? |
|
A one-component polyurethane foam
is a semi-rigid insulation material
produced for laymen and professionals
alike in various container sizes. |
| Q-002 |
|
What is
the chemical basis of a one-component
polyurethane foam? |
| The
chemical basis of a one-component
polyurethane foam is a prepolymer
from Polyol and Isocyanate. |
| Q-003 |
|
What is a
prepolymer? |
| A
prepolymer is a blend of the above
chemicals whose molecules have
already started to react with
each other. Once the reaction
is fully finished a new material,
which we call polyurethane, is
formed. |
| Q-004 |
|
Is it necessary
to support the chemical reaction
in any way? |
| Yes,
one-component polyurethane foams
need humidity for proper curing. |
| Q-005 |
|
How do we
add the required humidity to the
foam? |
| Once
extruded from the container, the
fresh foam takes humidity either
from the substrate to which it
has been applied and from the
atmosphere. |
| Q-006 |
|
Can the
curing process be supported or
accelerated in any way? |
| Yes,
by spraying water, preferably
with a flower spray, the curing
time of the fresh foam can be
reduced. |
| Q-007 |
|
How much
water does the foam need for proper
curing? |
| The
quantity of water depends on the
amount of foam that has been applied.
As a rule of thumb, approximately
40 millilitres of water are required
for a 750 millilitre can of foam. |
| Q-008 |
|
When does
the water have to be sprayed onto
the foam? |
| It
is advisable, to spray water onto
the surface/ substrate to which
the foam should be applied, and
then to spray also water onto
the fresh foam itself. Large quantities
of foam must be applied in layers,
and water must be sprayed onto
each layer. |
| Q-009 |
|
Is it necessary
to wait for each layer to cure
before applying the next layer
of foam and the water spray in
between? |
| No,
the contents of one full container
can be extruded all at once, if
in layers and if water is sprayed
onto each layer. |
| Q-010 |
|
Will the
fresh foam not be affected by
the water? |
| No,
the fresh foam will not be affected
in any way by the water. |
| Q-011 |
|
How much
water does one have to spray onto
the surface/substrate. |
| As
much as the substrate/surface
will absorb. There should be no
standing water on the substrate/surface
since water works as a repellent
to the foam and would deteriorate
the foams adherence to the surface. |
| Q-012 |
|
What happens,
if there is a lack of humidity
in the atmosphere and on the substrate
to which the foam is applied? |
| A
lack of humidity will lead to
insufficient curing of the foam
and may result in post-expansion
of the foam, even months after
the initial application. |
| Q-013 |
|
If a customer
complains about incorrectly cured
foam, is it possible to determine,
if there was a lack of humidity
during foam application? |
Yes,
if the applied foam is cut apart,
a discolouration from bright
beige (the foam’s normal colour)
to a brownish colour indicates
that there was a lack of humidity
during the application.
If the complaint is reported
shortly after the application
of the foam, it may be possible
to find an uncured brownish
sticky core within the foam
layer or bead. |
| Q-014 |
|
What is
properly cured foam resistant
to? |
| Properly
cured foam is resistant to water
- even salt water - vermin, rodents
and diluted acids, but it is not
resistant to UV-rays. |
| Q-015 |
|
Does the
non-resistance of foam to UV-rays
mean that the material cannot
be used outside? |
| No,
if the cured foam is painted over
or covered with mortar or Plaster
of Paris or any other coating,
it can be used outside without
any problem. |
| Q-016 |
|
What about
ageing of cured foam? |
| Cured
foam is resistant to ageing. There
is no destruction of the foam
as yet known, even after more
than 20 years since the first
foam was applied. |
| Q-017 |
|
Can joints
and gaps between insulation sheets
from polystyrene be finished up
with one-component polyurethane
foam? |
| Yes,
one-component polyurethane foam
can be used for that purpose and
the pu-foam does not affect polystyrene. |
| Q-018 |
|
Does one-component
polyurethane foam release any
hazardous fumes if cured and during
its life-time? |
| No,
cured one-component polyurethane
foam does not release any hazardous
fumes. |
| Q-019 |
|
What needs
to be considered if metal pipes
(steel, copper etc.) are covered
with one-component polyurethane
foam? |
| Metal
pipes have to be covered with
a coating since it is possible
that the open cell-structure at
the interface between foam and
metal surface - as a result of
condensation, caused by the media
running through the pipe - may
accelerate corrosion. |
| Q-020 |
|
Is it correct,
that the foam within the container
has a limited shelf-life? |
| Yes,
the foam within the container
has a limited shelflife due to
the chemical reaction that - though
very slowly - starts soon after
the chemicals are filled into
the container. |
| Q-021 |
|
Can the shelf-life
of a container be affected by
any external influences? |
|
Yes, if stored in warm places,
the shelf-life may be reduced
considerably - dependent on the
storage temperature. |
| Q-022 |
|
Will the
foam also be affected by lower
temperatures? |
| Yes,
lower storage temperatures have
a positive effect to the shelf-life. |
| Q-023 |
|
What happens
if, for some reason, a container
has been stored below zero for
some time? |
| The
viscosity of the contents of a
container, stored at or below
zero for some time, will increase,
i.e. the material becomes more
viscous. Thus the container has
to be warmed up prior to use.
This procedure may take quite
some time. |
| Q-024 |
|
Does the
storage or the application of
a one-component polyurethane foam
at temperatures below +5 °C have
any effect on the extruded foam? |
| Yes,
a foam bead extruded from a container
at normal temperatures (contents
above +5 °C) shows a creamy yellowish
appearance with an even circular
shape. The appearance of a bead
of foam extruded from a container’s
contents at lower temperatures
looks like frog spawn and has
an extremely coarse cell-structure
with transparent cells. The cured
foam isbrittle and of a brownish
colour. |
| Q-025 |
|
Is it possible
to accelerate the warming up process
in any way? |
| Yes,
it is best to stand the container
in lukewarm water. The warming
up process can be accelerated
by shaking the container from
time to time. |
| Q-026 |
|
Can the
warming up process be accelerated
by exposing the container to higher
temperatures? |
| By
no means should a container be
exposed to higher temperatures
since this will lead to a hazardous
increase of the pressure of the
propellant inside the container,
and may lead to an explosion of
the can. The safety instructions
within the warning box on the
container label must be observed. |
| Q-027 |
|
Is it possible
that a container may explode for
any reason if handled properly? |
| No,
under no circumstances will a
properly stored, handled and warmed
up container explode. Aerosol
containers are manufactured to
the highest industrial standards. |
| Q-028 |
|
Do aerosol
containers comply with specifications
regarding pressure (test-ressure/burst-pressure)? |
| Yes,
aerosol containers are manufactured
in Europe in compliance with the
German regulation TRG 300. This
regulation requires that an aerosol
of the type that is used for one-component
polyurethane foams withstands
a pressure test carried out at
15 bar. During the test the container
is exposed to that pressure for
25 seconds after which time it
must not show an irreversible
deformation of any kind. |
| Q-029 |
|
Is it possible
to determine from a burst container
if it was mishandled, wrongly
stored or exposed to extremely
high temperatures? |
| Yes,
according to the pressure tests
that have to be recorded for various
reasons (i.e. Manufacturers Product
Liability) it is possible to state,
that a container will burst at
or above 20-23 bar. Pressure of
this kind can only be generated
by the propellant in the container.
According to laws of physics the
pressure of a gas (propellant)
increases, if exposed to high
temperatures and drops as a result
of low temperatures. Each propellant
has its individual pressure temperature
profile. Hence it is possible
to gather from a chart the appropriate
temperature at which a propellant’s
pressure increases to 20-23 bar. |
| Q-030 |
|
Can the temperature
in a car increase to a level that
might become critical or dangerous
to an aerosol? |
|
Yes, tests that were carried out
by the German Automobile Club
some time ago, showed an increase
of temperature to well above +70
°C in a car on an average sunny
day in Central Europe. The inside
temperature can increase even
further, particularly behind windscreens
and rear windows with an inclination
at or below 45°. |
| Q-031 |
|
Does the
propellant in the container have
any negative effect on the ozone-layer? |
| No,
the propellant in the container
is approved worldwide. |
| Q-032 |
|
Our competitor
claims a higher yield of foam
from his container. |
| If
the container size and the type
of foam (i.e. gun grade, assembly
foam) is the same, there is very
little difference in the yield
of foam of containers from different
manufacturers. The yield depends
on various aspects for example,
age of container and yield test
method. |
| Q-033 |
|
How is the
age of a container contributing
to the yield? |
| As
a result of the polymerisation
that starts soon after the manufacture
of the container, the viscosity
of the prepolymer increases steadily
as time goes by. This process
takes place on a rather even level
during the first 6-7 months and
is accelerated towards the end
of the shelf-life. As already
stated, the storage conditions
can have a positive or negative
effect on the increase of the
prepolymer’s viscosity. |
| Q-034 |
|
How does
the viscosity of the prepolymer
affect the yield? |
| The
higher the viscosity of a liquid
or a polyurethane foam, the slower
its rate of flow. A viscous material
will not expand as well as a more
liquid one. Whilst the yield of
an older container is reduced,
the cell-structure of the foam
gets finer and thus better. |
| Q-035 |
|
Is there
any other factor that contributes
to the yield of a container in
respect of formulation? |
| Yes,
a very important factor in comparing
the yield of containers from different
sources seriously is the Specific
Gravity (SG) of the cured foam.
The higher the SG, the less the
yield from a given container size
and vice versa. The higher the
SG, the finer the cell structure.
Cured foam of a low SG has a coarse
cellstructure and hence has reduced
characteristics such as tensile
strength, compressibility, shear
strength and so on. |
| Q-036 |
|
What is
the Specific Gravity of a multipurpose
foam? |
| The
Specific Gravity of a multi-purpose
foam is 17-20 kg per cubic metre. |
| Q-037 |
|
Why is it
necessary to shake a one-component
polyurethane container prior to
use? |
| The
propellant in a one-component
polyurethane foam is being used
for three quite different purposes.
Firstly, it is acting as a solvent
to the high viscous prepolymer.
Secondly, it acts as a blowing
agent in the formulation. Thirdly,
it is needed to expel the prepolymer
from the container. A few hours
after the can filling, the then
homogenous solution of Isocyanate,
Polyol and Propellant starts to
separate. Hence it is necessary
to shake the container prior to
use, in order to regain homogeneity
of the solution. |
| Q-038 |
|
Is there
any adverse effect to the foam,
if the container has not been
shaken well prior to use? |
| Yes,
there is a very characteristic
appearance in the material expelled
from a container which has not,
or insufficiently, been shaken.
The material that cannot be called
foam, looks like frog spawn and/or
there is a clear separation of
the propellant (a white watery
liquid) from the prepolymer. |
| Q-039 |
|
Is it necessary
to shake the container during
use? |
| It
is advisable to shake the container
from time to time, in order to
avoid a separation of the propellant
from the prepolymer. |
| Q-040 |
|
How often
does a container have to be shaken
to obtain a homogenous blend? |
| A
container should be shaken at
least 15-20 times. |
| Q-041 |
|
The foam
which I wanted to apply from a
can I bought the other day expelled
from the can under much higher
pressure than the one from a container
I had used 6 months ago. You must
have overfilled the container. |
|
Safety propellants used in one-component
polyurethane foams have a specific
pressure which depends on temperature.
The type of propellant used in
our formulations, for instance,
generates a pressure of app. 6,5
bar at 20 °C. The pressure increases
if the propellant is exposed to
higher temperatures. It drops,
of course, at lower temperatures.
Even if the quantity of propellant
was twice the regular amount -
because of overfilling of the
container - its individual pressure
at given temperatures would not
increase. |
| Q-042 |
|
I was unable
to completely use the container,
that I bought yesterday, because
there was not enough propellant
in it. |
The
characteristic of a safety propellant
as being used in one-component
polyurethane foams is, that
its individual pressure at a
given temperature is stable
and - different from compressed
air, for instance - not dependent
on the filling quantity. If
we filled 2.000 millilitres
of compressed air into a pressurized
container with a volume of 1.000
millilitres, the pressure of
that compressed air would be
2 bar. Provided 500 millilitres
of that compressed air were
released from that container,
the pressure of the residual
compressed air would be 1,5
bar. If we released another
500 millilitres from that container,
the pressure of the remaining
compressed air would be 1 bar,
and so on. In other words, the
pressure of compressed gases
such as air, nitrogen, oxygen
and so on, correlates with the
volume of the container and
the filling quantity.
Liquefied safety propellants,
on the other hand, do not show
this characteristic. Their pressure
stays equal, regardless of the
volume of the container and
the filling contents. |
| Q-043 |
|
Is it necessary
to use a one-component polyurethane
container all at once? |
| No,
a partly used container can be
stored away for a few weeks, provided
the correct storage conditions
(dry and cool) are observed. |
| Q-044 |
|
How should
a partly used container be stored
away? |
Leave
the container in a dry and cool
place with the residuals of
cured foam in the valve stem.
The hardened foam in the stem
works as a seal against possible
loss of propellant.
|
| Q-045 |
|
What do
I have to do with the hardened
foam in the valve stem, if I want
to re-use the container? |
| Put
a woodscrew into the hardened
foam until it goes no further.
Then pull the cured foam out of
the stem. |
| Q-046 |
|
I was not
able to activate the container
I bought the other day. It was
not possible to tilt the valve
as described in the instruction
for use. |
| Valves
which are used for the manufacture
of aerosols are mass-produced
articles and cannot be checked
individually. Depending on the
storage conditions in the warehouses
of wholesalers or retailers (i.e.
at high relative humidity) humidity
can permeate into the container
over the time. Because humidity
works as an accelerator to the
prepolymer in the container, a
ring of cured prepolymer is formed
at the bottom of the stem, between
the black rubber plug of the valve,
which works as a spring, and the
stem. If the prepolymer ring is
still small and flexible, the
valve can be activated by tilting
the stem. If the stem can neither
be tilted nor be pressed down
vertically, it is best to return
the container to the retail shop
for replacement. A forcibly activated
valve may lead to an uncontrollable
extrusion of foam from the can
causing serious injury to the
user and damage of property. |
| Q-047 |
|
10 minutes
after I stopped work, foam was
still dripping from the adapter.
What did I do wrong? |
| You
did nothing wrong. The prepolymer
in the extension tube that expands
under the influence of humidity
in the atmosphere, and is thus
pushed out of the adapter. By
unscrewing the adapter immediately
after use, dripping of foam can
be avoided. |
| Q-048 |
|
How can
spilled foam be removed? |
Splashes
of fresh foam can be removed with
polyurethane cleaner or an adequate
solvent.
Hardened foam be removed with
PUREX. PUREX is a thixotrope gel,
which weakens the cured foam which
then can be removed from the spilled
surface. |
| Q-049 |
|
Does the
foam generate a pressure during
the expansion period until fully
cured? |
| Yes,
during the expansion period and
until fully cured, the foam develops
pressure as a result of its expansion.
Hence it is advisable to fill
gaps, voids and holes only to
approximately one third. |
| Q-050 |
|
What about
excess of hardened foam, around
a window or such like? |
| Excess
of hardened foam can easily be
trimmed with a sharp knife, cutter,
saw or similar. |
| Q-051 |
|
Is the hardened
foam watertight? |
| No,
hardened foam is not completely
watertight, particularly not where
it has been trimmed or cut. Though
the foam has a closed cell-structure,
the cut cells form voids which
can absorb water. |
| Q-052 |
|
Does the
cured foam have a thermal resistance? |
| Yes,
the cured foam is resistant to
temperatures from -40 °C to +100
°C (long-term) and from -40 °C
to +130 °C, short-term. |
| Q-053 |
|
Can the
foam be used to fill hollow profiles
(PVC, Aluminium, Steel etc.)? |
| It
is not advisable to fill hollow
profiles because the humidity
which the foam needs for a proper
cure, can not be provided over
the full length of the profile. |
| Q-054 |
|
What kind
of surfaces/substrates can the
foam be applied to? |
| One-component
polyurethane foam can be applied
to all firm surfaces/substrates
except for Polyethylene, Teflon_,
Silicone, oil and grease. |
| Q-055 |
|
What is
the recommended or best temperature
at which onecomponent polyurethane
foams should be used? |
| For
best results one-component polyurethane
foams should be used at +15 to
+25 °C (contents of container
and ambient air). |
| Q-056 |
|
What is
the expansion rate of the one-component
polyurethane foam which we buy
from your company? |
| One-component
polyurethane foams in aerosol
containers have an expansion rate
of approximately 150 %. |
| Q-057 |
|
What is
the water absorption rate of one-component
polyurethane foam? |
| The
water absorption rate of one-component
polyurethane foam is approximately
0,3%. |
| Q-058 |
|
What is
the elongation strength of a one-component
polyurethane foam? |
| The
elongation rate of one-component
polyurethane foam is approximately
18N/cm2 (DIN 53455). |
| Q-059 |
|
Does one-component
polyurethane foam have a tensile
strength? |
| Yes,
the tensile strength of one-component
polyurethane foam is approximately
20N/cm3 (DIN 53423). |
| Q-060 |
|
If , for
some reason, we wish to undertake
quality checks on the product
in our laboratory and exchange
test results with your Technical
Services Department, what are
the test conditions for being
able to comparing the findings? |
| All
tests on Technical Data stated
in our Technical Data Sheets have
been carried out at +20 °C and
a Relative Humidity of 60 %, surfaces
well dampened. |
| Q-061 |
|
Is there
a difference between the Specific
Gravity of onecomponent polyurethane
foam applied into a confined space
and one filled into a wide open
gap? |
|
Yes, the Specific Gravity of foam
applied into a confined space
is considerably higher than that
one of freely expanded foam. Due
to the confinement of the gap,
the cell-structure of the foam
becomes extremely fine. |
| Q-062 |
|
Does your
company manufacture in compliance
with any internationally accepted
QC-scheme? |
| Yes,
our company has been certified
according to the standards of
ISO 9001 in 1993. The follow-up
audit and the certification were
successfully carried out in August
1995. |
| Q-063 |
|
Why are
there so many different container
sizes of one-component polyurethane
foams available in the market? |
| One-component
polyurethane foams are available
in the market in various types
of systems. There is the standard
can which has to be used with
the valve and adapter facing upside
down. Then there is the piston
can, that is available from Polypag
AG only, since we hold a patent
for this type of can.
All the containers sold in
Europe have to be manufactured
in compliance with the EEC directive
(Filling standards for consumer
products). According to this
directive, aerosol containers
have to be filled at least 75
% of the container’s brim full
contents. With reference to
this regulation the following
filling contents apply:
Container
contents
brim full
|
Filling
contents |
| 1’000 ml |
750 ml |
| 800 ml |
600 ml |
| 650 ml |
500 ml |
| 520 ml |
400 ml |
| 405 ml |
300 ml |
These filling standards do
not apply in Australia. Whereas
the contents of aerosols world-wide
are filled by volume, Australian
directives require filling by
weight.
Different from the filling
standards for upside down containers,
piston cans are filled in compliance
with a sub chapter of the directive
for the filling of consumer
products. According to this,
a piston can is considered a
multi-chamber container, and
the following filling standards
apply:
Container
contents
brim full
|
Filling
contents |
| 1’000 ml |
825 ml |
| 800 ml |
560 ml |
| 650 ml |
470 ml |
|
| Q-064 |
|
Does the
one-component polyurethane foam
which we purchase from your company
have a fire rating? |
Yes,
our product has a rating according
to the German DIN 4102/part
1. The DIN 4102 specifies in
part 1 that all building materials
used in high rise buildings
must have a “Building materials
classification”. There are 3
classifications as follows:
| Classification
B3 |
lightly inflammable |
| Classification B2 |
normal inflammable |
| Classification B1 |
hardly inflammable |
Foam with classification B1
is currently not available from
any supplier world-wide, due
to technical reasons. |
| Q-065 |
|
How can
hardened one-component polyurethane
foam be removed from human skin? |
| It
is advisable to leave hardened
one-component polyurethane foam
residues untreated. Never use
abrasive items such as pumice
stone. The natural build-up of
cutaneous grease will shed the
foam within one or two days. |
| Q-066 |
|
A couple
of months after I used one-component
polyurethane foam to fill gaps
around uPVC-windows, the surface
of the window frame discoloured
partly. I did not cover the frame
before the application of the
foam, but I removed some foam
spillage with pu-cleaner from
the uPVC-frame. |
| One-component
polyurethane foam does not release
any agent that might discolour
uPVC or any other surface material.
Probably the foam spillage were
not fully removed from the uPVC-surface
and a very thin film of diluted
polyurethane remained on the frame.
In the course of the time this
thin layer of polyurethane became
discoloured by UV-rays - to which
the product is not resistant. |
| Q-067 |
|
The containers
you delivered last time produced
a foam of a bright beige colour.
The foam which I extruded from
today’s consignment showed a more
greyish appearance. Is there anything
wrong with this product? |
| No,
one of the substances in the product
is Isocyanate, which is a crude
oil derivative. Crude oil is supplied
to the refineries from different
countries around the world in
a vast variety of colours, and
so on. |
| Q-068 |
|
Does the
hardened foam have a thermal conductivity? |
| Yes,
the thermal conductivity of the
product is 0,04 W/mK. |
| Q-069 |
|
What about
the elongation at tear? |
| The
elongation at tear is 30 %, measured
in compliance with DIN 53455. |
| Q-070 |
|
What is
the shear strength of the hardened
foam? |
| The
shear strength, measured in compliance
with DIN 53422, is 8 N/cm2. |
| Q-071 |
|
What is
the bending strength of the hardened
foam? |
| The
flexural strength of the hardened
foam is 20 N/cm2 (DIN 53423). |
| Q-072 |
|
