Your Auto Trim Store Customers hear salespeople talk about “expanded” upholstery vinyl and wonder exactly what is being referred to. Expanded upholstery vinyl is a polyvinyl chloride material that has a layer of material with cells filled with air that are formed by releasing a blowing agent in the manufacturing process. Uniroyal, under their trade name Naugahyde, and the General Tire and Rubber Company, under their names Boltaflex and Nautolex, along with some other manufacturers, made expanded vinyl very popular over 50 years ago. Since that time, many manufacturers have made a lot of expanded vinyl.
Originally, expanded upholstery vinyl was created so that a vinyl coated fabric would have more thickness, or body, as it was called. In addition, it expanded the vinyl away from the backing, reducing the clothy look that a lot of early vinyl suffered from when it was just cast or calendered, then laminated. Expanding the vinyl made upholstery vinyl look more expensive and feel good to the touch, as well as made it appear more expensive. Also, embossing grains in those days were generally a lot deeper than today, and a thicker product was needed to really make those embossing grains pop.
The early expanded upholstery vinyl was made two ways that I know of. One way was to calender the vinyl in a tandem process while processing the eventual expanded layer at a moderate temperature less than 300 degrees Farenheit, then run it through another machine called an expansion machine that had an oven that would raise the temperature above the original processing temperature to the point that the vinyl would expand, usually around 340 degrees Farenheit. The expansion was caused by a blowing agent that had been put into the vinyl in the calender process. As the temperature rose, the agent would release small bubbles of gas, creating a foam like layer in the vinyl. An embossing roll used to provide the grain or texture to the vinyl then gap embossed the vinyl, giving it the finished texture. This method is not as popular today. It made a much tougher vinyl than today’s favored method, but the material in this process is not nearly as soft as most of today’s expanded vinyl, so it is not as much in demand as it was. Today’s expanded has pretty much evolved into a softer product, because of customer preferences. However, it is still produced for some applications. It is the material of choice for high impact upholstery such as athletic gyms and other applications that require a tougher product.
The method most used to make expanded upholstery vinyl today is a casting process. In this method, a very long machine is used to create the casting process. A liquid plasticized vinyl resin is applied onto release paper in this process. As the material is horizontal through the process, the plasticized vinyl is cured with heat and air flow. The fabric backing can be added during this process, or later in a laminating process. Again, the vinyl is expanded as the temperature rises in the process to the point where gas bubbles are formed, creating a foam like layer in the vinyl. The grain embossing comes from a texture designed into the release paper the material is casted on. While this method requires an expensive machine, it is still not usually as expensive as using calendering machines and expansion zones. For that reason, plus the enormous demand, there are many producers of this type expanded.