Typical Formulation Ingredients
Ingredient
Parts by weight
Polymeric methylene diisocyanate (PAPI 901, Dow Chemical)
Polypropylene glycol polyol (Titanol PPG 200, Cameo Chemicals)
Aluminum silicate (Glomax LL, Imerys Performance Materials)
Polyether amine (Jeffamine T-403, Huntsman)
(Source: Flick, E.W., Adhesive and Sealant Compound Formulations, Noyes Publications, 1984, p. 231)
Typical Properties
Mixing ratio (Part A:Part B) by weight
Viscosity increase
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Flexibility
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Resulting Properties
The formulation above is for a general purpose two component polyurethane adhesive based on polypropylene glycol. It has very good adhesion on metals and low surface energy substrates such as Teflon.
Often additives are not required to provide flexibility or toughness as in the case of epoxy formulations. Polyurethanes have the capability of providing these properties through manipulation of the resulting molecule by proper choice of isocyanate and polyol. However, additives are sometimes used mainly to stabilize the adhesive relative to moisture, oxidation, UV, etc.