What is polyurethane glue?
Single component moisture curing polyurethane glues and sealants, are very interesting products.
Upon exposure to moisture, these products cure, producing exceptionally strong films. The question is often asked, from where do single component polyurethane’s get the moisture………..from two possible sources, either from the moisture contained within one of the materials being glued, or from the atmosphere.
Wood typically contains approximately 11% water……..loads to get the chemical reaction moving. The atmosphere can contain perhaps 60% moisture, therefore there is ample moisture to kick start the chemical reaction. But what happens if we are gluing, say insulating foam to ABS plastic? Well in this case, there is normally enough moisture in the atmosphere. For applications where a fast sure time is required, it is possible to apply a mist coat of water onto the glue, before the second material is placed on the wet polyurethane glue.
When the moisture reacts with the polyurethane glue, a small quantity if Carbon dioxide gas is released during the cure process. In applying thin films of glue, this has no effect on the bonding process. However, if the humidity is high, or very thick films of glue are being applied, bubbles or blisters may become an issue.
When the polyurethane glue is applied, curing takes place from outside to inside at a rate of a few millimetres per day.
Don’t forget, when processing polyurethane glues or sealants, the “skinning time” must be adhered to. The ‘skinning time’, is the time after which the glue or sealant solidifies on its surface (forms a “skin”) and sticking to the second substrate is no longer possible.
In their cured state, many single component polyurethanes are elastic and flexible, this is why moisture curing, single component polyurethane systems are used where materials with widely differing elongation under loads and differing thermal coefficients of expansion. This is why our single component polyurethane sealants are commonly used with the bus, truck and rail sector.
Within our product portfolio, we have a range of liquid applied polyurethane glues, which are used in a wide range of industrial applications. As an example, in the manufacture of prefabricated buildings and in laying artificial sports surfaces. Our single component polyurethane sealants, find extensive us, in the manufacture of trailers, storage containers and also within marine applications.
For any application, our Chemist’s can offer the right polyurethane glue or indeed polyurethane sealant, for almost any application.