PRODUCT
LITERATURE
Composite
Molders
AXEL MoldWiz® internal mold
releases will...
· better wet reinforcements
· improve resin
flow
· eliminate buildup
· make mold release
easy
· improve dispersion
of color and filler
· eliminate stress
and flow marks
· improve cosmetic
surfaces
· yield clean parts,
ready for finishing
and for pultrusion, these added
benefits...
· reduce pull force
· improve line
speed
· eliminate chalking,
scaling and scumming
Internal Mold
Releases (IMRs) for Composite Molding
What is an IMR?
IMRs are materials which are
mixed directly into the resin to improve release properties
and also improve molding or processing characteristics.
They may also be added to gel coats.
Why are IMRs used?
In many cases, IMRs can make
using an external mold release unnecessary. Less time
spent applying mold release and cleaning molds can translate
into significant savings in production time. In addition,
IMRs contribute to better gloss and improved wetout of
reinforcements and fillers. In pultrusion processes, IMRs
reduce pull force and improve line speeds. When added
to gel coats, IMRs promote smoother, denser surfaces and
this contributes to higher gloss.
Are they suitable for all
molding applications?
IMRs require heat to function
as release agents. This heat can be generated by the exotherm
of the resin, by heated mold surfaces, or by elevated
process temperatures. Generally, applications which have
minimum temperatures of 150°F/65°C and use metal
molds are good candidates for internal mold releases.
With FRP molds, adding an IMR to the gel coat will reduce
porosity and improve release and appearance of parts,
although periodic use of external release agents is still
recommended to seal the porosity of the mold.
How do they promote release?
Axel's internal mold releases
are proprietary polymer products designed to be partially
compatible with resin. This permits some of the IMR to
cross-link with the resin during the cure, while the balance
is emitted as a vapor, creating the release interface
between part and mold. Inter-laminate strength, especially
the bond between the laminate and gel coat, is not weakened,
because the exothermic heat drives the vapor to the mold
surface.
Will IMRs effect the physical
properties of molded parts? Will it change their color?
When used in the recommended
additive range, IMRs can actually improve physical properties.
Because these materials tend to reduce resin viscosity
they permit the resin to wetout fiber better and this
results in correspondingly stronger matrixes. Better wetout
at the mold surface means smoother, glossier parts. Axel's
IMRs are effective at very low additive levels and generally
have no effect on resin color. If color or fillers are
being added to resin, IMRs will make it easier to disperse
these materials in the resin mix.
Do IMRs change gel times
or cure schedules?
Axel manufactures many different
IMRs. Each is resin and application specific. This vast
array of products allows us to match a lubricant to the
resin and cure which are being used, and this minimizes
the effect that the IMR has on gel times and resin cures.
We suggest that customers run gel tests with and without
lubricant to evaluate any changes prior to using the lubricant
in production. Should a radical change occur, a different
IMR should be considered.
If an internal mold release
is used, will parts need to be cleaned before they can
be painted or bonded?
Absolutely not. Molding cleaner
parts and having cleaner molds is a great reason to consider
an internal.
How are internals added
and how much is used?
Internal mold releases can
be added to the resin or gel coat by the manufacturer
or, they can be added by the end user or fabricator. Axel
manufactures IMRs in liquid, powder and pellet form. For
composite applications, liquid IMR is added to the less
viscous or reactive thermoset component before mixing.
The recommended starting point for evaluating mold releases
in these applications is 0.5% of the total system weight.
In highly filled resin systems, or processes like pultrusion,
the recommended range for IMRs can be 0.75% - 1.5%.
Can I use the same IMR in
different types of resin? How do I select the right product?
We wouldn't recommend it, and
thatís why we manufacture hundreds of formulations.
We believe in products engineered to enhance performance
and productivity, not generic solutions. Our technical
support group (800-332-AXEL, 9-5 EST) backed by our developmental
chemists will be pleased to recommend the right product
for you, or formulate one to meet your unique requirements.
What they will want to know is, what the molding conditions
are (temperatures, type of molds etc.), what resin is
being used and what type of cure or catalysts are involved.
Axel's Composite Molding focus sheet contains a useful
chart which describes some major resin/cure categories
and suitable MoldWiz internal lubricants. Popular products
include: INT-PS125 and INT-EQ6 for polyester and vinyl
ester, INT-1846N for amine cured epoxies, INT-1890M for
anhydride cured epoxies, and INT-XL51 and INT-389A for
gel coats.
MoldWiz is a registered trademark of Axel Plastic Research Laboratories, Inc.
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