How to extend pot life
Epoxies and Polyurethanes generate heat during
the reaction. Since these materials are very poor in conducting heat while in
liquid form this energy is retained within the mass of mixed product. This
retained energy intern will accelerate the reaction further resulting in the
generation of even more heat. The more reactive the system the more heat it will
generate during the curing process.
Hardeners, catalysts and similar components in
a given formulation are designed to yield a certain pot life at a specified
temperature for a specified mass of material. The best way to extend pot life is
to control the amount of energy (heat) that is available for the curing process.
Trade Off: The lower the temperature the
higher the viscosity. Pouring and de-airing are more difficult at lower
temperatures.
Two Component Materials (Manual mix):
-
Reduce the amount of heat generated while
mixing the components together.*
-
Reduce the amount mixed at one time.
-
Keep the mix cool.
-
Select a slower hardener.
* Violent, high speed, high shear type mixing
will raise the temperature of the mix.
Two Component Materials (Machine mix):
-
Lower the resin and hardener holding tank
temperatures.*
-
Lower the temperature on heated dispense
lines.*
-
Select a slower hardener.
-
Switch to a static mix head.**
* Lower temperatures will result in higher
viscosities and increased back pressures.
** Dynamic mix heads usually operate at high
rpm which generates heat due to the shearing action. Static mix heads do not
have moving parts and do not generate heat while mixing.
Single Component Materials:
The pot life of single component materials is
basically the same as the shelf life. This time period can be extended by
storing the material at cooler temperatures. The gel time can be slowed by using
cooler component parts or moulds in the application.
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Disclaimer: The above information is general in nature and is based solely on experiences by Crosslink Technology Inc. The recommendations provided herein may not be applicable in all situations. They are provided to the recipient as part of our customer service and the user must determine the relevance of the information to his/her application, considering any limitations that may be applicable thereto. Crosslink technology Inc. does not accept any liability for direct or consequential damages resulting from the the implementations of these recommendations or the use of this information.
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