Typical Formulation Ingredients
Phase
Ingredient
Parts by weight
A
Polycaprolactone (MW = 530)
A
50/50 o.p’ Methylene diphenyl diisocyanate
Typical Properties
Tg, °C, of the prepolymer
Green strength (30 min), lb/linear inch
Green strength (7 days), lbs
Resulting Properties
By being capable of curing to a thermosetting material, reactive hot melt adhesives eliminate or greatly reduce many of the performance problems associated with conventional hot melt adhesives. In addition, reactive hot melt adhesives have the ability to bond to many different substrates and, generally, have longer service life times.
Before the HMPUR adhesive reacts with ambient moisture, it must exhibit the properties of a conventional hot melt system. Typical application temperatures for HMPUR adhesives are in the range of 85°-140°C with melt viscosities from 2,000 to 80,000 cps. Application temperature and viscosity can be engineered by the balance of polyester and polyether components and the degree of amorphous structure in the polymer.
(Source: Polyurethanes: Science, Technology, Markets, and Trends by Mark F. Sonnenschein)