RAPRA TECHNOLOGY'S REFLECTS INTERNATIONAL RESPONSE TO REACH
17 July 2007 - Rapra Technology Limited

This year’s high attendance was perhaps reflective of the influence of new REACH legislation, higher requirements for better performance of rubber parts and the need to learn how to adjust to current market pressures.

Volker Boerger from Schill & Seilacher “Struktol” opened the conference with an important paper on how REACH will impact on the business of medium sized suppliers to the rubber industry. Volker’s presentation discussed the role of Schill & Seilacher as a producer of chemicals from overseas, a downstream user of raw materials and as a supplier to the rubber industry. Whilst Schill & Seilacher intends to ensure the existence of most of its products, this may not be true of all SMEs. With new regulations come higher costs for the approval of entirely new rubber chemicals. There is likely to be rationalisation of current additives due to the large costs needed to generate chemical safety reports and the production of rubber chemicals will be concentrated on the modification of approved products to bring performance improvements and broaden applications where possible.

The shadow of REACH was certainly present for the duration of the conference. The biggest developments were seen in the fillers and additives sectors and in the clever compounding of materials to achieve higher efficiency of the cure systems and meet environmental requirements.

Many papers presented alternative additives that could be used to replace unacceptable, but commonly used, chemicals for example ETU in CR (Rhein Chemie Rhenogran MTT-80 / Rhenogran HPCA-70); DOTG, a cure activator used in acrylic rubbers, ACM & AEM (Rhein Chemie Rhenogran GE 1986) and replacement of DPG in tyre compounds (Lanxess Vulcuren VP KA9188).

There were a number of papers on the use of fillers in rubber and their effects. This is an area where relatively great progress can be seen, especially in combination with silanes where silica fillers have increasing importance. Dr Ansarifar, Loughborough University, described a novel technique for preparing rubber formulations using crosslinked silanised precipitated silica nanofiller, to bring about improved mechanical properties of rubber vulcanisates. As a result there was a substantial reduction in the use of the curing chemicals without compromising the properties of rubber compounds.

Chris Stevens of NGF Europe Ltd presented work on the use of glass flake particles as fillers to enhance the permeation resistance of elastomer compounds. Sealing and barrier applications requiring low permeation, for instance nitrile rubber for fuel containment and chloroprene rubber for plant lining can benefit from the significant performance gains and cost reductions provided by using thinner barrier layers and/or extending barrier service life. Data presented by NGF Europe showed that 10 x reduction in water permeability could be achieved for polychloroprene with 15 phr glass flake (120 aspect ratio). This is expected to be significantly better than can be achieved with nanofillers. Trials in an NBR compound for a fuel hose application were not as successful.

Reporting on the great activity in developing more effective, environmentally friendly silanes, Oliver Klockmann from Degussa presented work on improved silica/silane technology for tread compounds used in passenger car tyres. Degussa has developed VP Si 363, a bifunctional organosilane which chemically bonds the silica to the rubber and meets new ecological and economical requirements for improved rolling resistance, fuel savings and lower CO2 emissions.

There followed a paper from Mizuho Maeda who described two crosslinkable plasticiser liquid rubbers developed by Kuraray. These improve processability, have less migration/ extraction by solvents and provide improved surface appearance.

Moving on to compounding and processing, Bhawan Patel from Milliken Speciality Elastomers gave a fascinating presentation on new FKM compounds for turbo charged hose liners. Fluoroelastomers have become increasingly important in withstanding high under the bonnet temperatures in combination with fuel/oil resistance and give adhesion strength to silicones and NR-latex compounds containing the curing and filler components as nano particles.

An alternative approach for conventional compounding was presented by Joseph Gnanamani. The Deutsches Institut für Kautschuktechnologie e.V in Hannover is developing a latex route to disperse fillers, in this case silica/silane, to produce a dry free flowing powder “rubber filler composite”. This can then be compounded via a twin screw extruder.

The final session of the conference was on testing to control the effects of rubber chemicals. A method to measure the carbon black dispersion via interferometric microscopy was delivered by Elmar Hartmann from Atomic Force F&E in Germany. Three dimensional topographic data yields surface roughness values that are correlated with the dispersion level of the carbon black in the compound and allow the dispersion index to be calculated by a rubber independent universal equation.

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