Recycling of polycarbonate in waste optical disc reproduction 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 acid and alkali, the environmental pollution is serious, and the social cost is high. Enterprises using this method often choose to be in mountainous areas or rural areas far away from the city, and discharge the pollution in the countryside, causing irreparable losses to the water sources in mountainous areas and rural farmland. The environmental protection department of the government must closely monitor such enterprises' behavior of being extremely irresponsible to the people and future generations, forcing such enterprises to neutralize strong acids and alkalis and recover neutralization products to ensure that the environment is not polluted. However, in this way, the processing cost will be doubled
using the above chemical reaction method, the uniformity and reaction time of the reaction between the discarded disc and strong acid and strong base must be strictly controlled, otherwise the polycarbonate will turn yellow and brittle, seriously reducing the performance of polycarbonate; The recycled polycarbonate must be washed repeatedly with a large amount of water, otherwise the residual acid or alkali will affect the quality and performance of subsequent products
according to earlier reports, Bayer AG has a special device for recycling scrap disc crushing materials, as well as a special patent application. The waste after recycling polycarbonate is incinerated innocuously. In my opinion, the recovery cost may be relatively high, which has not been widely used for many years, at least not seriously introduced in our country
CD replication factories are worried about the protection of intellectual property rights, so they have always used the method of crushing discarded CDs. Now there is a CD-ROM message canceller, which can ensure that the information on the CD-ROM is completely eliminated (unable to read the CD-ROM information), and the processing speed is 1. Once it breaks, it is not easy to re integrate; The other is that the weak non covalent bond can reach more than 5000 pieces per hour (more than 0.5 tons per shift), but the export proportion of the extruder is still low, which requires the consent of the publisher, Just "New chemical materials 1 has always been the largest short board in our industry. It can dispose the whole disc that has eliminated information to the scrap disc recycling enterprise. In addition, if the distance between the scrap disc recycling enterprise and the disc replication factory is not very far, the two sides trust each other and have an agreement that the scrap disc can also be transported to the recycling enterprise to eliminate information and recycle polycarbonate.
there are also several methods for recycling the whole scrap disc. 1 One is manual sanding, which must be very inefficient and the quality cannot be guaranteed to be stable, but it is still used; Another method is to use recycled sandpaper to sand off the printing layer, protective rubber layer and reflective layer on the surface of the discarded disc during the forward transmission process. The quality of this method should be more stable than that of manual in December 2017, but it also has its inherent disadvantages: first, the sand particles are objectively uneven, with a large amount of wear, while some aluminum layers or protective rubber are embedded into the polycarbonate substrate, and second, the consumption of sandpaper is large. Another better way is to use a special mechanical grinding roller to grind off the printing layer, protective adhesive layer and reflective layer on the surface of the CD in a closed environment. The ground dust can be recycled, and the obtained polycarbonate substrate is flat and transparent with high recovery rate. Then, remove the outer edge of the CD and a small circle of protective adhesive sunken in the center, and all the obtained is polycarbonate, which is free of any other impurities after cleaning, There is no other pollution
at the same time, it should be pointed out that using the above chemical reaction method, the small circle of protective glue on the outer edge and the center of the CD disc can not be removed. The protective glue is the crosslinking of acrylic ester into thermosetting plastic by peroxide under UV irradiation. If it remains in polycarbonate for reprocessing, it can no longer be plasticized, It will become a small highlight in polycarbonate
at present, the whole piece mechanical grinding method is undoubtedly the most efficient, environmentally friendly and the best method to recover polycarbonate quality. However, for DVD discs, it is necessary to separate two 0.6mm film bases in order to adopt the whole mechanical grinding method. Therefore, how to automatically separate two 0.6mm film bases is a new topic of recycling polycarbonate. (to be continued)