Recycling of recycled CDs in polycarbonate discs II

Using the above chemical reaction method, the direct cost is low, only about 500 yuan per ton. However, due to the use of strong acids and alkalis, the environmental pollution is serious and the social costs are high. Enterprises that use this method often choose rural areas that are farther away from the city or in the countryside, and discharge pollution into the countryside, causing irreparable damage to water resources in the mountains and farmland in rural areas. The government's environmental protection department must closely monitor this enterprise's extremely irresponsible behavior towards the people and the later generations, forcing the company to neutralize strong acid and alkali and recover the neutralized products to ensure that the environment is not contaminated. However, such processing costs will increase exponentially.

Using the above chemical reaction methods, the uniformity and reaction time of discarded discs reacted with strong acids and bases must be strictly controlled, otherwise the polycarbonate will be yellowed and brittle, and the performance of polycarbonates will be seriously reduced; recycled polycarbonate must be used. Repeated cleaning with plenty of water, otherwise residual acid or alkali will affect the quality and performance of subsequent products.

According to earlier reports, Bayer AG in Germany has a device for recycling discarded discs and discarded discs. It also has patents for special applications. The waste after recycling polycarbonate is burned without harm. I think that the cost of recovery may be relatively high, and it has not been widely used for many years, at least not in our country.

The CD replication factory is concerned about the protection of intellectual property rights, so it has been using the method of crushing discarded discs. Now that there is an optical disc destroyer, the information on the disc can be completely eliminated (the disc information cannot be read out), and the processing speed can reach more than 5,000 per hour (more than 0.5 tons per shift), as long as the publisher agrees. The entire disc that has eliminated the information can be disposed of to discarded disc recycling companies. In addition, if discarded disc recycling companies are not far away from the disc-copying factories, the two parties trust each other and have agreements, and they can also send discarded discs to recycling companies to eliminate information and recycle polycarbonate.

There are also several ways to recover the entire discarded disc. One is manual sanding, the efficiency is certainly low, and the quality cannot be guaranteed, but it is still used; the other uses recycled sandpaper to print and protect the surface of the disc during the forward transfer of discarded discs. The reflective layer is sanded off. The quality of this method should be more stable than manual ones, but it also has its inherent disadvantages. First, sand grains are objectively high and low, and the amount of abrasion is large. At the same time, some aluminum layers or protective glues are embedded in polycarbonate. Film base, and second, the consumption of sandpaper is relatively large. There is also a better way to use a special mechanical roller to grind away the printing layer, protective adhesive layer and reflective layer on the surface of the disc in a closed environment, and the dust can be recycled and used to obtain the polycarbonate sheet. The Kipping was transparent and the recovery rate was high. The outer edge of the CD disc and a small circle of protective colloid that was indented by the central boss were removed and all the polycarbonates obtained were polycarbonate. No impurities or any other contamination was observed after washing.

At the same time, it should be pointed out that using the above-mentioned chemical reaction method, the outer edge of the CD-ROM and a small circle of the protective rubber of the center-sweeping recess cannot be removed by the normal method. The protective glue is to be used under ultraviolet irradiation with peroxide. Acrylic resin cross-links into a thermosetting plastic, which can no longer be plasticized when it is reworked in polycarbonate, and will become a small highlight in polycarbonate.

At present, the method of using an entire piece of mechanical grinding is undoubtedly the most efficient, environmentally-friendly, and best-quality method for recovering polycarbonate. However, for DVD discs, two 0.6mm film bases must be separated in order to use the entire mechanical polishing method. Therefore, how to separate two 0.6mm film bases automatically is a new recycling process. Carbonate problem. (to be continued)