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Technology Focus

Recovery options for hot stamping foil scrap

by Staff

November-December, 1995
Is there value in your used hot stamping foil scrap? Maybe. The technologies are beginning to take shape and could offer the manufacturers and users of hot stamping foils new ways of disposing of their scrap polyester film in more environmentally acceptable ways than ever before. This article will cover some of the new options that have developed in the past 24 months, ranging from mechanical recycling to incinerations with energy recovery.

Mechanical Recovery
The biggest challenge in hot stamping foil scrap recovery has been finding a way to use the scrap in a secondary application. Almost all polyester films-based hot stamping foils are thin films, less than 2 mil in thickness, and thin films are very difficult to wash in a cost efficient manner. Therefore, the only markets that have developed so far are ones that can use the scrap with the inks and coatings still on the film, or when the inks and coatings can be easily removed. The markets are largely in the Far East, where demand for scrap polyester in all forms has been strong. However, there are some thin film washing technologies on the drawing boards right now that might be able to handle hot stamping foil scrap. So keep a close watch on the mechanical recovery market.

Chemical Recovery
Chemical recovery processes actually depolymerize the polyester film back to its raw materials, depending on the chemical process used. The most publicized, and one of the best options available today for much of the scrap foil, is the methanolysis unit that DuPont will be commissioning in the first quarter of 1996. Methanolysis is the process of turning polyester films into ethylene glycol and DMT (one of the basic routes to polyester). This unit will have the capacity to depolymerize 100 million pounds of scrap. DuPont's process will have the ability to handle up to 10% contaminants (in the case of hot stamping foils contamination, it includes the lacquer, release coating, metallization layer, and adhesives). So while not all scrap will fit DuPont's needs, some if it will. In speaking with DuPont, they are optimistic that many types of hot stamping foil scrap will be suitable for their process. We will have to wait until DuPont starts up the unit and begins the depolymerization process to see how well it actually will work with hot stamping foil products.

Another very promising depolymerization technology is being developed by United Resource Recovery Corp. in Spartanburg, SC. URRC's process can take polyester films with very high levels of contamination and depolymerize the polyester into ethylene glycol and teraphthalic acid (TA). URRC is looking to site a pilot facility at this time. The benefit to this kind of process is that it opens up the possibility to recover all hot stamping foil scrap because of the higher levels of contamination that it can accept. It should be noted that both Hoechst-Celanese and Kodak also operate methanolysis units but don't appear to be pursuing hot stamping foil scrap as feedstock at this time.

Waste to Energy Incineration
Many hot stamping foil manufacturers use this option already. It's a good one, especially if the scrap cannot be recovered any other way. The BTU value of polyester is more than twice that of coal, meaning it burns more completely and more efficiently. Polyester also burns much cleaner with far lower emissions. The costs for this type of disposal are relatively high, sometimes more than twice the cost to dispose of the material in a landfill, but someone is at least realizing the value of the films inherent energy.

So Where's the Value?
The polyester film scrap market is like any other market for recyclables - it moves up and down with time and is affected by many outside influences. From the price of raw materials to whether or not China has enough cotton to meet the demand for its textile market can affect the overall market. However, a value may be created when the market is ready to pay hot stamping foil manufacturers for the scrap that they are currently landfilling or incinerating. There is some evidence that recyclers will take scrap at no cost or even pay a couple of cents when markets for scrap polyester are strong, as they have been in 1995. So the value is the disposal cost avoided PLUS any revenue that a recycler might offer. For a hot stamping foil user who disposes of 500,000 pounds of polyester film scrap per year (let's assume a disposal cost of 2 cents per pound). This means a bottom line swing of 4 cents per pound. On 500,000 pounds of scrap, that is $40,000 of value. It can be done and, in fact, is being done in certain places right now.

To the hot stamping foil manufacturers, look to your polyester film suppliers for solutions. Many of them are gearing up to handle the questions of the afterlife of polyester film and to offer usable answers. To the users of hot stamping foil, look for the opportunities to get value out of your scrap polyester film. The market is working to develop opportunities to minimize the environmental issues surrounding polyester films, and hopefully, creating some value at the same time.

Jeff McGlaughlin is a Product Life Cycle Specialist for ICI Films. ICI Films is a leader in specialty polyester films and film surface pretreatments, manufactured in North America in Hopewell, VA. ICI Films markets a range of polyester films under the trade name Melinex® and is a business unit of ICI Americas Inc.