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Beautifully dull

A new additive mixed in with synthetic rubber guarantees more beautiful footwear soles

Exclusive to rustic footwear used for heavy tasks, rubberized soles took to the streets some years ago in masculine and sophisticated feminine models, of well known national and international brand names. If initially it was very shiny, and identified with synthetic materials such as plastic, today it is dull and can be confused with leather, one of the most highly valued raw materials. In order to arrive at this almost equal mimicry, an additive mixed in with the elastic material, also known as synthetic rubber, playa a fundamental role. The product provided to the Brazilian market has basically come from two companies, one North American and the other Japanese. This has been happening up until now, but Rhodia Brasil is planning to launch by 2007 a new additive to compete with those imported, this being the result of a research project supported by FAPESP through the Partnership for Technological Innovation (PITE) program, in conjunction with the Chemical Engineering Faculty of Lorena (Faenquil).

The product is being manufactured on a pilot scale and tested by companies that are Rhodia clients under the condition of confidentiality. “Some clients have approved the product and want to know when it’ll be on the market”, related the chemist Leo dos Santos, who participated in the project with a post-doctorate grant from FAPESP and today, contracted by the company, is looking after the final adjustments of the formula make up. Interest for the new additive is justified. In the end, as the product will be manufactured here in Brazil, it will have a competitive price in relation to that imported.

Energy spending
The idea of developing an additive to be mixed with elastomers came about from Rhodia Brasil itself in order to give a better destiny to a by-product of phenol, namely the alpha-methyl-styrene monomer, one of the molecules that form the polymer from which the soles of tennis shoes and footwear are made. Phenol is a chemical compound that can start off a chain reaction in the production of a polyamide, more commonly known as naylon, with application in carpets, female underwear, sports clothes, cabinets for electro-electronic apparatus and various other products. Part of the alpha-methyl-styrene is sold pure so that it can be applied in the manufacture of adhesives and resins. That which is left over, and this represents a large quantity, comes back as the raw material for the production of phenol, after having passed through a recycling process that involves a large amount of energy.

As well as phenol, Rhodia Brasil also produces silica that is used in the elastomer industry as a reinforcement for improving rubber’s mechanical properties, guaranteeing resistance to abrasion, traction and tearing. “But, on incorporating silica into synthetic rubber an elevated increase in the material’s viscosity occurs, which makes its processing difficult. For this reason it’s necessary to put in an additive that improves the fluidity of the elastomer”, advised professor Amilton Martins dos Santos, from Faenquil, who is the project’s coordinator. As some of these additives have alpha-methyl-styrene in their formula, Kenneth Wong, a chemist who has worked at Rhodia Brazil since 2001, the era in which the project began to take shape, suggested the integral use of the by-product of phenol.

Professor Martins dos Santos was chosen as the project’s coordinator at the faculty because, as well as acting as a company consultant, he is a specialist in a techniques called polymerization in emulsion, the most indicated technique to incorporate the monomer alpha-methyl-styrene into a polymer chain. “The polymerization process by emulsion was originally developed as an attempt by man to imitate the latex of natural rubber”, advised coordinator Martins dos Santos. Synthetic latex, the result of the aqueous dispersion of polymer particles stabilized by surfactants, chemical substances that act upon detergents, is used in various industrial sectors to manufacture paints, adhesives, additives and other products.

In the beginning the proposal was to make a silica particle covered with alpha-methyl-styrene. As this is a study that demands a long time period, the researchers decided right from the start to concentrate on a determination of a formula for the additive and the best mix of the raw materials that would go to make up the composition of the final mixture. “In the formula, as well as the process conditions, such as temperature and percentage of raw materials, there are the correct surfactants, responsible for stabilizing the polymer, which make all the difference”, advised Richard Macret, the Research and Development (R&D) director at Rhodia for Latin America.

Pilot scale
Initially, on a laboratory scale, some grams of the additive were produced. Today, when some better formula mixtures have been chosen, twenty (20) kilogram samples of the product are being provided to clients and this product can be mixed into various types of rubber and other polymers. Depending on the target market – footwear soles, bicycle tires, stackers, conveyor belts, straps and other applications still being studies -, the formula mixture has a different composition. “We have to look at the impact of these products in the various markets”, advised director Macret. “And this is a relatively long time study.”

The footwear sector is the first on the list. “We already have an appropriate formula mix and now we’re researching to know what the most advantageous process, economically speaking, might be”, said coordinator Leo dos Santos. The choice is justified because for Rhodia this is a market for which it provides a varied selection of products, which run from  the treatment of leather, glue for shoes, up to silica for rubber. Last year the company’s sales for this sector attained around US$ 60 million, corresponding to 8% of the annual total income of Rhodia Brasil, which was some US$ 750 million. The goal is to grow some 10% in sales over the next few years.

The company’s wager is that the additive could help to increase even more its participation in this market. This is without counting that the by-product in the production of phenol, recycled with large energy spending or sent for disposed of within the environmental regulations, has shown that it can be transformed into a new commercial product at the level of those imported.

The Project
Synthesis and description  of co-polymers of alpha-methyl-styrene looking towards its application in the  encapsulating of silica particles (nº 01/11114-0); Modality Partnership for Technological Innovation (PITE); Coordinator Amilton Martins dos Santos – Faenquil; Investment R$ 35,850.00 and US$ 1,120.00 (FAPESP) and R$ 64,997.00 (Rhodia)