Perlon U

This particular polymer is a fibre-forming material (Perlon U). Although in many respects this reaction resembles the formation of polyesters and polyamides it is not a condensation reaction but involves a transfer of hydrogen atoms and thus may be considered as an example of rearrangement polymerisation. 

Compared with nylon 66 fibres, the polyurethane fibres (known as Perlon U) have a tensile strength at the higher end of the range quoted for nylon 66, they are less prone to discolouration in air, are more resistant to acid conditions and they have a lower moisture absorption. On the debit side they are less easy to dye, are hard, wiry and harsh to handle and have too low a softening point for many applications. They are currently of little importance but have found some use in bristles, filler cloths, sieves and a few other miscellaneous applications. 

Perkins, William H., 19 423 Perlite, asbestos substitute, 3 314t Perlman, David, 11 50 Perlon U, 25 455... 

Polyurethane fibres (Perlon U) were prepared by reacting hexamethylene disocyanate with 1,4 butanediol in 1942. Because they were difficult to dye and had harsh feel so went out of the market. But these resins are used for small mechanical components like gears and bearings because of dimensional stability and retention of electrical resistance in humid conditions. 

The nonaromatic PU shown in structure 4.68 is sold under the trade name Perlon U. As in the case with nylons and polyesters, higher melting products are formed when the number of carbon atoms is even since this allows a closer packing of the chains. 

Mixtures of isocyanates are commonly used for convenience in commercial production of the diisocyanate, since the pure toluene 2,4-diisocyanate is more expensive to produce. The resulting prepolymer is then mixed with either a glycol, such as 1,6-hexanediol, or a deactivated (sterically hindered) diamine plus pigment if required, and then promptly poured into a preheated mold of the desired shape. In about half an hour the mixture sets to a pliable shape with stiffness and elasticity controlled by the components and processing details used [29]. Similar procedures produce high-strength polyurethane fiber (e.g., Perlon U) or elastomeric fibers (e.g., Spandex and Lycra). 

Perlon U, which was manufactured in Germany to a small extent, is a polyurethane. It is formed by the action of hexamethylene di-isocyanate on 1 4 butanediol. d he butanediol is obtained by the action of formaldehyde on acetylene followed by reduction ... 

If the functionality of the reagents exceeds unity polymers will form. Thus, the use of di-isocyanates and dihydric alcohols (glycols) give the fundamental polyurethanes. One of the first of these was an early synthetic fibre Perlon U, made by Bayer from 1,4 butane diol and hexamethylene diisocyanate ... 

Linear products result if the reactants are bifunctional, as in the case of Perlon U. Higher functionality leads to the formation of branched chain or crosslinked materials. This tendency is enhanced by the additional reaction of the isocyanate with the urethane, urea, or amide groups already introduced during initial polymer formation, reactions (a), (b), (c) above. The hydrogen on the urethane, urea or amide group is still active, and attacks a further isocyanate group. 

Polyurethanes were first discovered by Otto Bayer and coworkers at I. G. Farbenindustrie, Germany, in the late 1930s. The first products were obtained by reacting an aliphatic diisocyanate with an aliphatic diamine or diol. These materials soon found commercial uses and were marketed under the trade names of Irgamid U, for plastics, and Perlon U for synthetic fibers and bristles. Very soon after this, it was discovered that isocyanates could be used to bond rubber to metal, which in turn led to the development of urethane adhesives based on polyester diols these adhesives were commercialized under the trade name Polystal. For a more complete account of the history of polyurethanes, see refs. 2, 4, and 5. 

Thermoplastic urethane elastomers are products derived from the basic urethane polymer work conducted since 1937 by Professor Otto Bayer and co-workers in Germany. The first commercial uses of solid urethane polymers were synthetic fibers and bristles in Germany under the trademark of Perlon U thermoplastics under the trademark Igamid U. Later investigations led to the development of the Vulkollan cast urethane elastomers and the Multrathane cast systems at Mobay Chemical Company. In 1961, Mobay introduced Texin urethane elastomer resins for injection molding and extrusion on thermoplastic equipment. 

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