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Material engineering

Recycled plastic

Discarded packaging is used for labels and books

miguel boyayan Synthetic paper whose thickness and texture are similar to pulp papermiguel boyayan

Synthetic paper manufactured from post-consumption discarded plastic was developed at the Federal University of São Carlos/UFSCar and tested at a pilot plant owned by Vitopel, a company that manufactures flexible films. Vitopel has a plant in the town of Votorantim, São Paulo State. Produced in the form of film, the material is made from water bottles, food containers and cleaning products packaging. It can be used for bottle labels, billboards, board games, stickers, school books and money bills. “It is indicated for applications that need properties such as protection from water and humidity; in addition, this material is very resistant,” says professor Sati Manrich, from UFSCar’s Department of Materials Engineering and coordinator of the project which received funding from FAPESP for the development of the research and the filing of the patent. The plastic currently being marketed is made from oil by-products. “Various patents have been filed and products are being sold that are based on virgin raw material, but we have not found any patent for or synthetic paper made from recycled plastic,” says Sati.

The tests at the pilot plant, also referred to as semi-industrial scale, were conducted by Lorenzo Giacomazzi, Vitopel’s coordinator of processes technology. Vicopel is the co-holder of the patent. “The outstanding characteristic of this process is that the synthetic paper is made from totally recycled material,” says Giacomazzi. Various compounds and mixed plastic from the polyolefin class were used. “The product looks exactly like the product made from new resin; the advantage is that our product is made from material that would otherwise end up in landfills or garbage dumps.” The negotiation of the patent was based on an exchange between two parties. A partnership was agreed upon, because the company had to know the composition of the material to give permission for its equipment to be used. “We didn’t pay anything to use the machine necessary for the experiment and, in exchange, they kept one third of the intellectual property,” explains Sati. The company is currently looking for suppliers of recycled material to continue the tests on a broader scale.

In the process developed at the university, the plastics are first cleaned and grinded. Mineral particles are then added to provide them with optic properties – shine, whiteness, contrast, light dispersion and absorption – and mechanical resistance to tears, traction and folds. The mixture is then placed inside an extrusion machine at a very high temperature, where it softens and melts. Finally, the material transforms itself into a big, thin sheet of paper, similar to a sheet of paper made from pulp. The sheet is rolled and cut according to the given application.

The tests at the pilot plant were made with the plastic blends that showed the best properties, in lab tests, for the manufacturing of synthetic paper. For comparative purposes, the optical properties and the results of printing on paper made from new raw material and plastic residues were evaluated. “The tests showed that the properties of the synthetic paper made from recycled material remained virtually the same,” Sati reports. Differences in the bleached coloring were found only in the synthetic paper which had been based on dark color plastics.

The researcher’s interest in this subject dates from 1996, when she began working on a project funded by FAPESP; the project involved characterizing polyolefin from urban residues for the manufacturing of synthetic paper. Since then, Sati has coordinated a number of research projects focused on recycling packaging which had been discarded after consumption. Two of these projects resulted in the filing of patents for the manufacturing of synthetic paper, but the processes and materials currently being used are different. The original process uses PET (polyethylene therephthalate) bottles, and requires an additional stage, which consists of a chemical treatment to produce the film. The second research project, which began in 2002 and is considered an improvement over the first project, is the synthetic paper tested at Vitopel.

The projects
1. Studies on multilayered films made from new and recycled thermoplastic compounds for writing and printing applications (nº 03/06113-0); Type Regular Aid for Research Project; Coordinator Sati Manrich – UFSCar; Investment R$ 69,518.53 (FAPESP)
2. Synthetic paper and eco-friendly films for writing and printing, compositions, guidance processes and uses thereof (nº 06/58862-4); Type Support Program for Intellectual Property; Coordinator Sati Manrich – UFSCar; Investment R$ 7,479.00 (FAPESP)