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materials engineering

More competitive plastics

Partnership between OPP and IPEN produces high resistance polypropylene and easy to recycle

eduardo cesarPolypropylene: more elasticity, resistance and easiness in recyclingeduardo cesar

A process that makes plastic products easier to produce and to recycle is the result of a project between the Nuclear and Energy Research Institute – IPEN and OPP Química, a company belonging to the Odebrecht group, working within FAPESP’s Partnership Program for Technological Innovation (PITE). As a consequence of the joint research, three patents have already been registered that involve the procedures and the products obtained. The focal point of the project is a synthesis process for polypropylene of highmelt resistance. This resistance refers to the liquid phase of this material after the original solid resin is transformed, in a machine called an extruder. This happens before the final molding of the plastic product. What the researchers managed to do was to give more elasticity to the polypropylene during the melted phase.

This type of material, known as HMS-PP (high melt strength polypropylene), has been taking over the market, above all in Europe, for environmental reasons, where the industry has starting using it in the manufacturing of sponges for various uses, mainly in car dashboard, because they are easier to be recycled. “The parts produced from the mixture of diverse other plastic resins offer too many obstacles to recycling, making them unfeasible viable”, explains Ademar Benévolo Lugão, the project’s coordinator from the Chemical Engineering and Environmental Department of IPEN.

In Brazil, dashboards are still made from components of polypropylene with elements of polyethylene, polyurethane, PVC and ABS. All of these materials are thermoplastic, which with the thermosetting – such as epoxy resin, for example – and the elastomers, a category that covers all rubbers, make up the family of polymers. Or that is to say: they composed of organic macromolecules, which, in a general manner, are made by linking together basic units called monomers which look like a long string or chain. The polymers are synthesized by the cross-linking of these chains, forming a type of network, in immense industrial reactors.

In polypropylene, originating from the monomer propylene, the linkage force between the molecules is low. Its totally linear structure determines that the material is highly fluid, and difficult to process in the molten state, which inhibits its application in some molding techniques and in the production of special foams. “From the start, we even thought of making the molten polypropylene more elastic by increasing the size of the molecule and thus creating a tangle of molecules”, recalls Lugão. “However, we managed to obtain better results inserting fragments of polypropylene with the polypropylene itself through irradiation with a cobalt-60 source. These ramifications of the long chain created a much higher amount of cross-linking. It is almost like a dish of long spaghetti. The longer and more subdivided they are, the more entangled they become, making the resin process easier.”

In the first phase of the project, which began in 1999 and was concluded a few months ago, small sources of cobalt radiation were used, typical of test laboratories. Afterwards,when the tests took on a larger scale, the IPEN called upon the services of the Empresa Brasileira de Radiação (Brazilian Radiation Company – Embrarad) in the town of Cotia (SP), which provide gamma radiation using cobalt-60 to diverse economic segments. “Embrarad’s contribution was fundamental”, emphasizes Lugão.

According to the researcher, taking as a reference the fluidity index, the resistance of the molten polypropylene multiplied itself by between fifteen and thirty, while the current technologies available in the developed countries can produce a multiplication effect of between eight and ten. “From the point of view of the quality of the material, we’re perfectly prepared to supply the future demand of the most demanding users”, celebrates Alexandre Elias, product engineer at the OPP Química and the company’s liaison officer with the IPEN. Elias believes that the demand for HMS-PP will be a trend absolute consolidated in the Brazilian market within, at the maximum, five years.

Market and scale
“We intend to start commercial production before this date”, he observes. For now, the OPP and the IPEN are continuing to project their efforts towards improving the methodology and to reducing production costs, which for Lugão, are still high. In the vision of the OPP, the development of the market for HMS-PP in Brazil depends on the car makers. “Its use in vehicles will give the necessary scale of production for the dissemination of other possible applications”, forecasts Elias.

For example, among them are extruded sheets – those that pass through the liquid process and are solidified before molding – used for the manufacture of large size parts such as rubbish bins, furniture, boxes etc. “Actually, there are opportunities in all of the segments in which polypropylene has not been to win expressive participation due to its semi-crystalline constitution, which imposes limits to its transformation and in its low resistance”, postulates Lugão.

Polypropylene, commercialized since the 60’s, has been registering the highest market growth among plastic polymers. Produced in almost fifty countries, it has an annual sales volume of more than thirty million tons. Data from Solvay, the gigantic international petrochemical company, indicates that 33% of this total is used in packaging manufacture.

In the developed countries, the applications for which HMS-PP has a potential, consume close to one million tons of polymer every year, taking into consideration the physical sales of polystyrene, high impact polystyrene, PVC, low density and high density polyethylene and ABS, among others, explains Lugão. In Brazil, this market represents, more or less, something around 30,000 tons per year, according to OPP’s estimates. The value of HMS-PP could surpass by US$ 100 the price of a ton of conventional polypropylene.

As well, he highlights the emergence of new applications in the area of packaging of pre-cooked food for the micro oven, in which the HMS-PP could compete with polyethylene terephthalate (PET) better known as the raw material for plastic soft drink bottles. “The environment regulations are producing two trends: the reduction of solid waste, and the increase in the recycled fraction of this waste”, he says. “The HSM-PP could contribute to the consolidation of both, because it can provide greater thickness control, thus leading to the production of packaging with thinner walls, and it presents a lot less of recycling problems than PVC, widely used in the production of tubing and connections, casings in buildings, floors and linings.”

Advanced product
In the area of PVC, obtained through the polymerization of vinyl chloride, the OPP is also preparing to serve an increase in demand – it could in fact double its production, which today is around 400,000 tons per year, close to 60% of the commercialized volume of the country.

Last November the OPP received the Finep Award for Technological Innovation in the process category, for the development, jointly with the Technology Research Institute (IPT), of an automatic temperature control system in the PVC reactors. Another aspect of the project was the coupling of reflux condensers automatically brought into action when the temperature rises above previously established limits, depending on the characteristics to be obtained in the product.

The process has already been implemented in three of the company’s reactors in Camaçari, in the state of Bahia, reducing the PVC’s synthesis time from twelve hours to only three and a half hours, producing a productivity increase in the order of 80%. “As well as this, we got a gain in quality as process control improvements obviously make standards compliance much easier”, says Lucien Rebello dos Santos, responsible for the process development in the PVC division of OPP. “Another aspect in which there has been noticeable improvements is safety: we’ve managed to reduce risks to people and to the equipment.”

The coming together of the company and the Institute started back in 1994 and grew in a well planned manner. In that year, Marcos Alberto Castelhano Bruno, today the executive director of the IPT and responsible for the administration of partnerships with companies, was studying the case of the petrochemical company of Camaçari, in his doctorate thesis on company administration, which dealt with the interaction between the academic and corporate worlds, with their advantages and challenges. The control of the company shares moved into the hands of the Odebrecht Group in 1995, when the government began privatization in the petrochemical sector (read the box about the OPP).

Common sense
“The partnership consolidated itself during 1997 with a program for the administrative formation of the company’s technicians in order to qualify them in interchanges with institutes and universities”, recalls Bruno. This first step, says Santos, was fundamental for the definition of each of the parts and the generation of knowledge coming from common effort. “Without this probably we wouldn’t have managed to evolve so much”, he reflects.

From the company point of view, an important ingredient in the success recipe of the project was the preservation of aspects of the traditional technology of polymerization – the installation of reflux condensers was the only alteration to which the equipment was submitted. “We used common sense, avoiding both the necessity of making large investments in capital goods and increasing the consumption of energy in the process”, observes Santos.

During the concluding phase of the project, which all in all lasted about one and a half years, two IPT researchers spent about one month in Camaçari, following OPP’s operation, firstly on a pilot plant, and finally in the company’s industrial reactors. One of the big challenges was to transform the measurements of the laboratory reactor to those needed in the industrial phase. “A second prototype is ten times larger than that produced in the laboratory, and the industrial company doubled its size. Together we learned how to change scale”, sums up Santos.

On the track of mergers and innovation

The OPP Química company will be changing its name to Braskem by the end of the year, with the merge of the Companhia Petroquímica do Nordeste (Copene) from Camaçari, which the Odebrecht Group bought in 2001, in association with the Mariani Group. At the same time in which the company life might be described as a succession of merges and acquisitions clearly driven by the strategy of the conglomerate from the construction industry to make itself present in all of the links of the petrochemical productivity chain sector, the constant search for technological innovation is one of its registered trademarks.

“In research activities aimed at result multiplication, cost reduction and a productivity increase, we’ve invested more than US$ 70 million in R&D over the last ten years”, says rmed Antônio Bragança, OPP’s technology director. The company employs one hundred and seventeen researchers, of whom six have their doctorate and around twenty are at the level of masters. They maintain agreements on development of technologies with diverse research institutes and universities.

Besides the IPEN and the IPT, the company’s extensive list of partnerships with academic institutions includes, for example, the São Paulo State University of Campinas (Unicamp), the Federal University of São Carlos, the Alberto Luiz Coimbra Institute of Post Graduation and Research (Coppe) of the Federal University of Rio de Janeiro, and the Catholic Pontifical University of Rio Grande do Sul. “Sometimes we also work with foreign universities such as Wisconsin in the United States and Waterloo in Canada.”

In Braga’s opinion, OPP doesn’t come up against problems due to the difference in the working speed between the academic and the company worlds. “Assuming that the planning is good and the differences respected, there is an understanding and the two sides end up winning”, he emphasizes. Lucien Rebello dos Santos, responsible for the development of procedures in the PVC division, says about OPP’s R&D policy, that going to the universities and research institutes to carry out projects on mastering long term technologies is part of it, even if they don’t generate immediate results. “This interchange brings with it knowledge that at some time in the future will be put to good use.”

South American leader in the production of thermoplastic polymers and sodium hydroxide-chlorine for the manufacture of PVC and other products from paraffins and additives, OPP, who holds 27.3% of the capital of Copesul, the center of the petrochemical hub in Triunfo (RS), has six operational units in that region, three in the state of Bahia, two in Alagoas and one in São Paulo. In order to carry out tests on the products and technologies on a large scale, the OPP makes use of four pilot plants – three in Rio Grande do Sul and one in Bahia.

The OPP was taken over by the Odebrecht Group in the middle of the 90’s, shortly after the acquisition of the controlling stakes of Trikem, the name of the old Companhia Petroquímica of Camaçari in 1995. Afterwards the two companies merged their administration. The purchase of Copesul and of Copene has consolidated the importance of the group on the Brazilian petrochemical scenario.

The OPP has not released its financial results since the closing of the capital by the Odebrecht Group in May 2000. Braskem will be a listed company with its shares on the stock market.

The project
Development of a New Synthesis Process for Polypropylene with High Melt Resistance (nº 97/02390-6); Modality Technological Innovation Partnership (PITE); Coordinator Ademar Benévolo Lugão – IPEN;
Investment R$ 36,500.00 and US$ 67,360.00 (FAPESP) and R$ 136,000.00 (OPP)