Polyurethanes coatings and adhesives

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. 

Niax PWB-1200. [Union Carbide] Polyether polyol us to mfg. waterborne polyurethane coatings and adhesives. 

Chem. Descrip. Linear poly (1,6-hexanediol neopentyl glycol adipate) Uses PU intermediate for durable polyurethane coatings and adhesives Features Can be formulated into either water- or solv.-borne systems appropriate for outdoor applies, when reacted with an aliphatic isocyanate... 

Other uses for depolymerized PET bottles have been investigated. Used bottles have been glycolized and then used to make unsaturated polyester thermosets and polyol components in rigid polyurethane foam. Evco Research announced in 1999 its EvCote waterproof coatings and adhesives based on recycled PET [17, 18]. 

Polyurethanes are useful in numerous applications such as reaction injection molding, rigid and flexible foams, coatings and adhesives. However, due to the high reactivity of the isocyanate group [96], yielding either dimers, via self-condensation or a carbamate via the reaction with an alcohol, the A,jB-monomers have to be produced in-situ in the reaction vessel. 

What kind of stakes are involved A 1979 "Outlook" annual market survey by the Upjohn Company indicates that the total United States market for polyurethanes would be 2,1+1+1+ million pounds including 1,1+50 million pounds for flexible foam, 615 million for rigid foam and 379 million for elastomers, coatings and adhesives. 

This paper is a commercial survey covering recent developments in urethane coatings and adhesives with reduced solvent contents. There are many aspects of urethane chemistry which make polyurethanes an ideal base for nonsolvent coatings developments. However, in order to achieve practical handling behavior for coatings adhesives, modifications of classical urethane chemistry are needed. 

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. 

Other functional moieties. Other functional moieties that are in the polyurethane coating or adhesive will have a large effect on its properties. These exert both a qualitative and a quantitative effect. This means that as the relative ratio of urethane moiety diminishes, the coating will behave more nearly like the class of coating as defined by the major functional moiety content. Table VI provides a listing together with each formula. 

Texthane. [Morton IntT.] Polyurethane sol ns. textile coating and adhesive prods. 

Polyurethanes are widely used in several important applications including foams, elastomers, coatings, and adhesives. They result from the reaction between an alcohol and an isocyanate, and from this reaction, hyperbranched polymers can also be prepared from AB2 monomers having both functional groups in the proper ratio. The high reactivity of isocyanates, even in self-condensation, can lead to the formation of dimer or carbamates by reaction with... 

Thermoplastic polyurethanes exhibit good abrasion and mar resistance. They are stable to attack by oxygen and hydrocarbons, but are sensitive to moisture and acidic and basic solutions, which can result in hydrolytic chain scission. They are used as coatings and adhesives and in footwear and automotive parts. 

Phosgene produced by chlorinating carbon monoxide is used as a carbonylating agent to convert amines to isocyanates, as shown by reactions (8) and (9). Thus, the reaction of phosgene with diphenylmethane diamine results in the formation of methylene diphenyl diisocyanate (MDI), and with toluenediamine to form toluene diisocyanate (TDI). The isocyanates are used to produce polyurethanes for flexible and rigid foams, elastomers, coatings, and adhesives, for the construction and automotive industries. 

The major applications for polyurethane catalysts are in flexible and rigid foam, which account for over 80% of the catalyst consumption. Other applications are in microcellular reaction injection-molded (RIM) urethanes for automobile bumpers and a variety of noncellular end uses such as solid elastomers, coatings, and adhesives. 

Polyurethanes are formed in the reaction of isocyanates with polyols. The most important commercial aromatic isocyanates are toluenediisocyanate (TDI), diphenylmethane diisocyanate (MDI) and naphthalene diisocyanate (NDI), while the important aliphatic isocyanate is hexamethylene diisocyanate (HDI). Cycloaliphatic isocyanates of industrial importance are isophorone diisocyanate (IPDI) and hydrogenated MDI (HMDI). A number of triisocyanates, such as triphenylmethane triisocyanate, are used in coatings and adhesives. 

Several kinds of polyurethanes are of commercial significance and are conveniently classified into the following major types - flexible foams rigid foams elastomers fibres and moulding compositions surface coatings and adhesives. These various types of material are considered separately in this chapter after an account of the development of polyurethanes, the raw materials involved and the general reactions of isocyanates. 

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