Free isocyanates

Keywords spray foam, isocyanate free, silane terminated, prepolymers... 

Summary As all conventional spray foams contain monomeric isocyanates, they can present toxicological hazards. Therefore, an isocyanate-ftee substitute for these foams has been developed. This isocyanate-free foam is cured by a crosslinking reaction of silane-terminated prepolymers (STPs). This silane crosslinking system exhibits some new properties, and several problems occur that are completely unknown with ordinary isocyanate spray foams. In particular, crack formation during foam curing turns out to be a crucial problem. Therefore it was necessary to develop modified STPs and to use special STP-propellant mixtures. 

Reactive Extrusion and Isocyanate-Free Polyurethane Chemistry... 

Uses Film-former, clear coat for leather, paper, plastics and synthetics Features Crosslinkable low VOC isocyanate-free produces tough, flexible coating exc. chem./water resist. exc. adhesion to PVC, nylon, polyester fibers and films curable R.T. or elevated temps. 

Features Self-crosslinking low cosf low VOC isocyanate-free produces tough, flexible film, high adhesion, good chem./wafer/abrasion resist. Properties Wh. emulsion mild odor dens. 8.4 Ib/gal vise. 250 cps pH 8.0 00.5 VOC < 15 g/l Dry film props. fens. sfr. 4000 psi elong. 450% ( break) mod. 100% elong. 1100 psi 35 01% solids Ecco Rez U-27 [Eastern Color Chem.]... 

However, isocyanate reactants are very toxic and could entail adverse health effects such as asthma, dermatitis, conjunctivitis, and acute poisoning [313]. Hence, the synthesis of isocyanate-free polyurethanes is of great interest. Accordingly, an isocyanate-free method and new synthesis procedure has been developed to prepare... 

Polyurethane-Based Prepolymers Terminated with Silane-Compounds These prepolymers were based on the same chemistry and the same preparation procedure as all prepolymers mentioned above. But the isocyanate end group was reacted with a silane compound. These prepolymers are isocyanate free and have a different cross-linking mechanism. Adhesives based on these prepolymers are commonly used as sealants. They have good elongation properties, good adhesion to different kinds of materials and are usually more resistant against UV rays. They are not mixable with PU prepolymers of any kind. 

Polywax 1000 was used as nucleating agent in an isocyanate free UV curable hot melt composition. The coating is particnlarly useful in wood-working and furniture applications. ... 

These are two-pack cold-cure coatings and can be a blend of acrylic and epoxy resins for use with ferrous and non-ferrous metals as well as plastics. Designed to be applied by spraying to suitably pre-treated surfaces they are available as an isocyanate-free alternative to two-pack polyurethane systems. 

Weather-resistant epoxy acrylic 44 50 2 h 2-3 h Two components, topcoat, excellent weathering resistance, color and gloss retention, isocyanate-free... 

PU synthesized through an isocyanate-free method has been recently reported by Besse et al. They obtained linear and branched bio-based PU from isosorbide with acceptable thermal stability suitable for coatings applications. Isosorbide, extracted from the dehydration of sorbitol, as HS provides a good rigidity to the polymer [68]. Moreover, Besse et al. studied new bio-based isocyanate-free PUs with good thermal stability for coatings [68]. These PUs do not release isocyanate during the thermal decomposition. 

An isocyanate-free route to obtain carbamoyl derivatives implies the use of carbonyl bis-caprolactam (CBC ), a nontoxic... 

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