Conti, Kordsa partner on adhesion system

HANOVER, Germany—Continental A.G.'s tire division and Kordsa Inc. recently entered into a joint initiative to develop a sustainable adhesion system standard for bonding textile reinforcing materials to rubber-based compounds.

The two companies aim to have a free licensing concept and replace resorcinol and formaldehyde with more eco-friendly chemicals for adhesion. Continental and Kordsa worked together previously on other projects in the tire textile reinforcement market.

"We knew from each other that taking sustainable and responsible action is a key component of both companies' corporate strategies," said Ibrahim Ozgur Yildirim, chief technology officer at Kordsa.

Yildirim said the use of resorcinol and formaldehyde represents a major challenge to the tire industry. Kordsa seeks to find ways to make its tire manufacturing processes as environmentally friendly as possible.

Continental also is working to change the process.

"Employees in tire plants and end consumers don't get in contact with resorcinol and formaldehyde as they react to a network bound within the polymer matrix of the respective reinforcement material/tire part," said Boris Mergell, Conti senior vice president of research and development for passenger and light truck tires.

"If at all, exposure to the chemicals mentioned might only be possible at the converting process. This production step is done at the textile supplier and ensures adhesion of the textile reinforcing materials to rubber-based compounds. Therefore, the use of eco-friendly materials for the converting process is an important action with regard to environmental aspects and, of course, in the interests of our employees."

The resorcinol-formaldehyde system has been a standard for decades, with adhesion results that fill the increasing demand regarding endurance for tires in today's applications, Mergell said.

"In addition, tire plants and end consumers have no direct benefit if textile converters are using eco-friendly dip systems as the dipped and heat-treated fabric as delivered to the tire plant does not contain any free resorcinol or formaldehyde even with the current dip system," he added.

"This only affects the manufacturing process at the converter. Against this background it is understandable, without going into specific numbers, that it was a well-prepared and carefully considered decision of both companies to start working on the replacement of the standard dip system."

Both companies have their own dip facilities. The goal is to have a progressive introduction of the innovative technology in the production in tires across all segments; a substantial step toward greater sustainability, Mergell said.

The companies' desire to create a more sustainable adhesion system for the textile reinforcement material market is not a new quest.

Kordsa has been working in the field since 2008.

"Even with joined forces of both companies, this long period of development time for the new technology still is not finished," Yildirim said.

Until now, no adhesion technology was able to replace the standard dip system using resorcinol and formaldehyde by an environmentally friendly solution without sacrificing any performance measure.

"The goal is to introduce the free licensing concept for the new adhesion system so that the eco-friendly technology in combination with the free licensing concept so that Continental and Kordsa can further improve safety, health and the environment," Mergell said.

"The release process for such a new adhesion technology is very extensive, and we still have to realize some steps before we can start to implement it."

Both companies declined to disclose the monetary investment for the joint development, but noted it affects lab and production dipping units, including capacities of test laboratories for both companies.

"Continental has to build and test the new technology according to a complex and extensive approval process in tires to ensure that the latest status of technology can be offered without compromising any performance," Mergell said.

"Capacities are always an investment of time and money. Of course, we had and still have other usual financial investments to take related to textile conversion and tire building and testing. In the future, both companies will also have to make significant investments for the changeover to the new dip technology."

More information will be presented at the Tire Expo 2018 scheduled for February in Hanover.