Solventless polyurethanes

Most laminators use solventless polyurethanes. The composition and comparative properties of typical products are summarised in Table 16.3. 

First-generation solventless polyurethane adhesives are one-component isocyanate terminated prepolymers formed by the reaction of MDI (4,4 methylene bis (phenyl isocyanate)), or other isocyanates with polyether and/ or polyester polyols. One-component 100% solids adhesives rely on moisture from the air or substrates or from induced moisture misting during the converting process, to cure the adhesive via an isocyanate/water reaction and subsequent polyurea-polyurethane polymer formation. Typically the high viscosity of the adhesive is such as to require adhesive delivery equipment and application rollers heated from 65-80 °C for use. They have a high level... 

Second-generation solventless polyurethane adhesives Two-component second-generation adhesive systems are the most widely used of the 100% solids products. These two-part adhesives comprise an isocyanate terminated prepolymer based on the reaction product normally of MDI and polyols (polyether or polyester) in the presence of excess isocyanate, and a polyol (polyether or polyester based). 

Components of solventless polyurethane adhesives Aliphatic isocyanates used in polyurethane adhesives include ... 

The polyurethane derivatives used in solventless coatings and adhesives systems form a relatively small part of the market. There were about 50 million pounds sales in 1979, however, the solventless segment can be expected to grow at more than the 10fa rate expected for all polyurethane coatings adhesives. 

There is no industry guide to answer these questions. This has led many users of both solvent containing and solventless technology to hire their own polyurethane chemical experts and to produce their own multitude of proprietary variants. 

We have described the current state of the industry market in solventless polyurethane coatings and adhesives. There is a wide variety of specialty materials available, all selling for widely different prices and consisting of a wide variety of chemical compositions. 

Eastman Chemical (UK) Ltd for the coil coating enamel formula in Table 13.3 and the polyester epoxy powder formulae in Table 14.4. Shell Chemicals for the can coating formula in Table 14.1 and the electrodeposition primer formula in Table 14.2. CIBA Polymers for the solventless epoxy formula in Table 14.3. Cargill Blagden for the one-pack polyurethane formulae in Tables 15.1 and 15.2. UCB sa for the UV-curing acrylic formula in Table 16.2. 

Polystyrene and polyurethane foam and mineral wool tiles are applied to interior and exterior for decoration and insulation purposes (sound and heat). Solventless adhesives based on poly(vinyl acetate), polyacrylate, or styrene-butadiene copolymer emulsions are preferred for this purpose. The viscosity of the adhesives must be adjusted to give the required wet tack. 

Solventless, semiflexible, one-part Solventless, semirigid, chemical resistant, low dielectric constant Solvable, for hermetic electric motors Polyurethane coating... 

Depending on their use and characteristics, solvent or solventless polyurethane based adhesives are available and can also be customised for special packaging requirements. Some typical uses for one-component PUR adhesives are for adhesion of shopping bags, printed films, and adhesives for snack food bags. These are especially suitable for these applications mainly because they are solvent free, moisture curable, and easy to apply. 

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