Where be urethane?

What is called urethane in common parlance, is synonymous with the slightly more technical terms polyurethane, and urethane resin. A great variety of what are also called urethane plastics are possible. Various urethane resins are used in so-called "molded-plastic" products, in the form of flexible and rigid foams, in a variety of tough, protective, long-wearing coatings, either transparent or hiding, and as adhesives.

Some of the molded products that urethane resins are made into are described as being  urethane "rubbers." "Urethane rubber" is the very dense, strong, tough  material that modern automobile bumpers are often made out of. Such bumpers are often colored to match the car's paint color, and one might erroneously assume they are painted sheet-metal if one were only to look at them, and not handle them. They are tougher and less elastic than the "rubber" that automobile tires are made out of, but have more rubbery, elastic properties than most "plastics." The steering wheels of modern cars are also usually made out of urethane resin. You can dig your finger nail into a urethane steering wheel, something you can't do with the hard resin steering wheel on an older car.

Neothane is a trade name for cast urethane used for solid-"rubber" tires (as opposed to pneumatic tires, which are not made from urethane). For example handtruck wheels, used to move furniture, sometimes have urethane tires.

Urethane foam is a similar urethane resin, to the urethane used in dense molded urethane products, its distinction being that it is foamed, during the manufacturing process, by adding a compound that produces carbon dioxide when reacting with the urethane being manufactured. Urethane foam is the material used for cushions and pillows that has now all but replaced latex foam. This is flexible urethane foam. Rigid urethane foam is used for insulation.

The Spandex fibers used in elastic cloth are urethane fibers. Spandex is white, and dyable. Spandex-containing elastic cloth is often the cloth used in the elastic portions of clothing.

Urethane "varnishes" have found widespread use as tough coatings for wood floors, and have to a great degree replaced the other varnishes used to coat wood floors. They are also used as coatings for wood furniture. The older varnishes consisted of various resins dissolved in oil solvents, and after being spread on the floor or funrniture they hardened  by evaporation or oxidation, or both, of the oil solvent. There are 6 types of urethane coatings. Urethane coatings type 1,2, 3, and 6, cure by oxidation, reaction with atmospheric moisture, or heat. Urethane coatings type 4 and 5 are catalyst-cured.

Urethane resins are the strongest and hardest elastomers. Elastomer, in case you are interested, is the technical term for synthetic "rubber."

Urethanes (as well as aliphatic polyesters, and low molecular weight unbranched polyethylene derivatives) can be made into biodegradable plastics. Most other plastics are immune to enzyme attack (the chemicals that micro-organisms secrete, to decompose materials they "want to" assimilate), and thus cannot be made biodegradable. However some other plastics are photodegradable. Others are water-soluble, and thus can be "washed" away.
 

Where did urethane come from, and how did it get here?

No, it didn't get here by traveling long distances, from another planet, or another solar system. Rather, one way it got here is it appeared when someone reacted urea with an alcohol. Another way it got here, is it appeared when someone reacted isocyanates with alcohols or carboxy compounds (Brady and Clauser, page 820), or with "carboxylic" compounds (page 822).

But that doesn't really tell us much about how urethane got here, unless we know how urea, isocyanates, carboxy compounds, carboxylic compounds, and alcohols — got here. And they didn't come from another planet either. A note: urea is sometimes called carbamide. And urethanes are sometimes called alkyl carbamates.

The urea of commerce is made from ammonia and carbon dioxide, or from cyanamide.

The ammonia of commerce is made from aerial nitrogen and hydrogen (see the article on nitrogen for information about how nitrogen is extracted from the air). Cyanamide is made by reacting aerial nitrogen with calcium carbide. Hydrogen is obtained from often natural gas. Calcium carbide is made from limestone and coke or natural gas. Coke is made from coal.

Alcohols are a large group, an array, of chemically-related organic compounds. They are made by fermentation of green-plant products, or from natural gas, or from petroleum hydrocarbons.

What's left is to figure out is where isocyanates come from, and where carboxy compounds and carboxylic compounds come from. 

Brady and Clauser state that "isocyanates are esters of isocyanic acid... which does not appear independently."  It goes on to state that "dibasic diisocyanate... is made from a 36-carbon fatty acid."

By definition a fat is an ester of glycerol or other alcohol, and 3 fatty acids. I believe that a lipid is an ester of an alcohol and a number of fatty acids, but I'm not sure. I  believe this would mean that isocyanic acid is a fatty acid, and isocyanates are fats, or lipids, but I'm not sure.

However Brady and Clauser state that "isocyanic acid does not appear independently." This suggests that isocyanates are somehow obtained from fats, or lipids, or from fatty acids, but I am just guessing. Fats of course can be either from animal or vegetable sources, or from mineral sources such as petroleum. 

I also don't know what the sources of carboxy compounds, and carboxylic compounds, are. All I know is that "carboxyl groups" are found in all organic acids including amino acids, and fatty acids. Amino acids can be derived from proteins and fatty acids can be derived from fats or lipids.

Why do I think this?

Much of this information came from The Materials Handbook, 11th edition, by George S. Brady, and Henry R. Clauser, McGaw-Hill, 1951-1977. However George and Henry did not provide a convenient list of the raw materials that one would need to gather up if one wanted to produce urethane. I had to read how urethane was produced from various chemicals; then I had to read, in other chapters, how each of the various chemicals was produced; then I had to read how the chemicals that went into the various chemicals -- how they were produced, etcetera; until I came to materials that people either scooped out of the earth, the air, or the water; or cultivated agriculturally; or gathered; or hunted for.

The information about the definition of  lipids, fats, and fatty acids, came from Matter, Energy and Life, by Jeffrey J W Baker and Garland E Allen, Addison-Wesley, 1965.

Trying to trace this commercial material, urethane, to its Earthly Origins, and appreciating the complexity of the paths that were taken from raw materials to commercial materials, and from commercial materials to more commercial materials, has made me wonder if any single individual could be a repository of enough chemical-engineering knowhow to make urethane himself or herself from "scratch." 

Soilman Theodore Zuckerman