Energy savings plus mechanical reinforcement and rheology control

Moisture Cure Solvent Borne Polyurethane - Coal Tar Sealant

Adhesives Formulation

Applicable Type

Reactive Adhesives , Polyurethane Adhesives

Applicable Base Polymer

Polyurethanes

Applicable Industrial Sectors

Buildings & constructions

Applicable Base Polymer Properties

Polyurethanes are extensively and successfully used as adhesives and sealants, and they have an excellent record of durability. Polyurethane-based adhesives form tough bonds with high peel strength. They have better low temperature strength than other adhesives. They have exceptionally high strength at cryogenic temperatures. They have good chemical resistance, although not generally as good as epoxies or acrylics. Urethanes do not have high temperature resistance.

Typical Formulation Ingredients

Ingredient

Parts by weight

Polyurethane (Desmodur E-type resin, Bayer)

xxxxx

KC-261 coal tar

xxxxx

p-toluenesulfonyl isocyanate

xxxx

Organoclay (Bentone 34 gel, Elementis)

xxxxx

Magnesium aluminum silicate (Cyprufil 325, Mistron)

xxxxx

Xylene

xxxx

Adhesion promoter

xxx

Moisture scavenger (Additive OF, Borchers)

xxx

(Source: Amstock, J.S., Handbook of Adhesives and Sealants In Construction, McGraw-Hill, New York, 2000, p. 12.16)

Typical Properties

Properties

Solids by weight, %

xxxx

VOC, lbs / gal

xxx

Density, lb / gal

xxxx

Viscosity at 25°C, Kreb units

xxxx

Processing

Resulting Properties

The formulation above is for a polyurethane sealant heavily modified with coal tar. Often additives are not required to provide flexibility or toughness. Polyurethanes have the capability of providing these properties through manipulation of the resulting molecule by proper choice of isocyanate and polyol. However, additives are used mainly to stabilize the adhesive relative to moisture, oxidation, UV, etc. The formulation above is a single component, moisture curing urethane designed for low temperature and immersion application. It is high solids and VOC compliant. It is superior to coal tar epoxy for flexibility, weathering, corrosion resistance, heat resistance, and impact resistance.

Tips and Tricks

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