The world market for synthetic acrylic fibers used by the textile industry for making clothes, curtains, carpets and soft toys, often as a substitute for, or mixed with, natural fibers like cotton and wool, is estimated at 2.5 million tons a year. China, the biggest manufacturer, produced 839,000 tons in 2007 and exports its goods all over the planet. These fibers, which were launched at the beginning of the 1950’s by North American company, Du Pont, come from oil-derived raw materials and since that time have been manufactured by the original process: before being transformed into thread the polyacrylonitrile polymer (PAN) has to be dissolved in expensive and toxic solvents, among which are dimethylformamide (DMF) and dimethylacetamide (DMAc). This is a production process that may be superseded by another that has been developed by São Paulo company, Quimlab Química, whose headquarters are in São José dos Campos.
In times of greater environmental concern and production sustainability, the new process is an innovation in as much as it uses the waste glycerin left over from the manufacture of biodiesel instead of solvents. The use of glycerin as an additive allows the polymer to be dissolved without being degraded (which is not what happens when solvents are employed) and to be used for manufacturing not only synthetic fibers, but also a series of other plastic products, like packaging, bags and bottles. The new type of polymer derived from PAN is called Thermpan. Quimlab has already deposited three patents for the new process, one of them international, and development of the product is at the pilot-production stage. If all goes well within two years the industrial phase will begin. “We’re confident that our product, called Thermpan, will be very well received by the market”, says chemical engineer, Elson Garcia, one of the researchers responsible for this discovery.
Quimlab is a traditional producer of chemical patterns, mainly used for quality control in industrial processes. Set up in 1997, and until 2003 located in the technology incubator at the University of the Vale do Paraíba (Univap), the company is likely to license this new process for producing acrylic fibers to another company. Environmental and economic appeal is a strong ally of Quimlab, because by dispensing with the use of solvents, which are toxic to the environment and man, the process becomes less time-consuming, cheaper and cleaner. “The use of DMF or any other solvent demands that a step is created for dissolving it and another for washing the acrylic filaments and extracting the solvent. Finally, a third stage is necessary; the distillation and recovery of the solvent so that it can be reused for manufacturing the fibers”, explains Garcia. “In the production of Thermpan, the PAN polymer is plasticized in glycols, among them glycerin, and that’s why it can be dissolved and produce thread directly in a conventional extruder, which molds the dissolved material without generating toxic waste that needs to be recovered. The glycols become part of the product”, adds chemist, Nilton Pereira Alves, a partner in Quimlab. With the growth of glycerin (and of other plasticizers, which for reasons of industrial secrecy, cannot be revealed) Thermpan is capable of being dissolved with another polymer, for example polyvinyl chlorate (PVC), which is widely used in the manufacturer of pipes, water tanks, toys, gloves and hosepipes. It, therefore, opens up possibilities for new materials.
By using glycerin as a plasticizer, the substance that interacts with the polymeric chain by modifying its thermal behavior, the company is giving a noble end to a by-product from the production of biodiesel – for each 1000 liters of fuel produced, some 100 liters of glycerin are left over. According to the Brazilian Chemical Industry Association (Abiquim), the annual consumption of glycerin in the country, mainly by the pharmaceutical, cosmetic, food and chemical industries, is in the order of 40,000 tons annually, compared to an estimated production at 250,000 tons by 2013. This volume needs to have a destination, at the risk of becoming yet another environmental problem, although glycerin can also be burned to produce electricity.
“We’re forecasting that the production of acrylic fibers by Thermpan will have a potential market for using any excess glycerin made during the biodiesel chain. Today, this is dealt with as waste and is cheap”, Alves points out. To use the raw glycerin from biodiesel to produce acrylic fibers – the ideal thing is to use highly pure glycerin – Quimlab has developed a process that allows them to obtain a 97% purity level and gives excellent plasticization with PAN, without needing to go through the distillation stage. Samples of raw glycerin as a paste, produced by the Bioverde diesel plant in Taubaté, São Paulo, have been purified by this method and successfully used to produce acrylic fibers from Thermpan.
Research into the development of the new process and Thermpan started in 2004 and the first patent was deposited with the National Institute for Industrial Property (INPI) in 2006 and the international one in the following year. The third was deposited in October 2008, also in Brazil. Quimlab’s great innovation was to manage to dissolve the PAN acrylic polymer, which in essence was considered insoluble or thermofixed, which means it’s not moldable. When it was submitted to a temperature of approximately 200°C, the white powder, what PAN is like in its original state, breaks down and changes into black waste with a high level of carbon. By adding the glycerin as a plasticizer, the polymer can then be dissolved and processed in conventional machines used for making thermoplastic fiber thread. At the end of the 1990’s German multinational, Basf, developed a process and equipment using water as the plasticizing element, but according to researchers from Quimlab, it was not successful. “Because it uses water the extruder, the equipment that transforms the polymeric powder into thread, needs to work at a very high temperature and pressure, which makes the process technically unfeasible”, explains Elson Garcia.
Miguel Boyayan“The process we created is more economical and allows us to explore new markets. The raw material (in this case PAN polymer) represents 70% of the value of the synthetic fiber sold in the market. The other 30% are the transformation costs. With Thermpan, we hope to reduce the final cost of the fiber by at least 10%”, says Garcia. “We’re at the pilot-scale phase, with an approximate production of 2 kilos an hour. We?ve already presented our innovation to some companies, among which is Radicifibras, also in São José dos Campos, a manufacturer of acrylic fibers with capacity to produce up to 40,000 tons a year. They’re interested in the technology but prefer us to get further along with the process development and then we’ll talk again”, says Alves. He estimates that within two years the process will be concluded and Thermpan can be passed on to any industry interested in producing and selling it.
Although the main application of Thermpan is related to the production of acrylic fibers for the textile industry the company wants to explore other markets, with technological and commercial applications, and is even leaving open the participation of researchers from universities and research institutes who are looking for new uses for the material. Because of its physical and mechanical characteristics it can be molded into any shape or format, such as sheets, tubes, films and injected parts, as well as being used for manufacturing plastic packaging, bottles and bags, thereby competing directly with PVC, which also needs to be plasticized to become soluble.
With financial help from FAPESP, by means of a project in its Innovative Research in Micro and Small Companies (Pipe) program, Quimlab is also developing substances that are the forerunners of low cost carbon fiber, an acrylic product with a chemical composition that is suitable for allowing it to be transformed into pre-oxidized carbon fibers, known as Panox. These are used for making fireproof clothes that are widely used by firemen, soldiers and Formula 1 drivers. They can also be used for manufacturing seats for airplanes, automobiles, buses and trains, because they limit the spread of fire. This is an expensive and sophisticated material that, so far, is not produced in Brazil.
Carbon fibers also have a huge application in the aircraft, space, oil and sporting materials industries; the latter uses them as raw material for tennis rackets and golf clubs, for example. “Embraer uses 10% carbon fiber in the fuselage of their aircraft, a percentage that rises to 50% in the case of the jets made by Boeing and Airbus”, says Elson Garcia. At the end of last year Quimlab managed to produce the first threads of carbon fiber, but it is still working on achieving the necessary physical and mechanical characteristics. Students and teachers from the post-graduate program of the Aeronautical Technology Institute (ITA), in São José dos Campos are also taking part in this work, which is also supported by the National Council for Scientific and Technological Development (CNPq), through its Human Resources in Strategic Areas (RHAE) program. The latter is investing R$150,000 in two year scholarships for three of the institution’s Masters degree graduates to undertake fiber-related research. “Under the coordination of professor Luiz Cláudio Pardini, they are characterizing and determining the properties of Thermpan, mainly with the aim of it being used to produce carbon fiber”, says Alves.
Another partner institution of Quimlab in the carbon fibers’ project is the Marine Technology Center (CTM). “We have been formally assured of support by the CTM, which is developing a project for the production of this type of synthetic fiber. Shortly, we should be sending the first samples of our fibers for them to carry out the carbonization and physical and chemical trials in their laboratories”, explains Nilton Alves. The CTM is studying the use of carbon fibers for producing enriched uranium and the submarines that Brazil manufactures.
Development of the process for producing acrylic polymer thread by fusion for the production of precursors of carbon fiber (nº 06/60733-8); Modality Innovative research in Micro and Small Companies (Pipe); Coordinator Elson Garcia – Quimlab; Investment R$ 98,000.00 (FAPESP)