CdF-Chemie

Metathesis of alkenes is essentially a class of reactions where an interchange of C atoms between pairs of double bonds takes place. A few representative examples are shown by the reactions listed in Fig. 7.10. The industrial use of metathesis reactions so far has been limited mainly to exchange metathesis (Fig. 7.10, top, backward reaction) as in the SHOP process, and ring-open metathesis polymerization (ROMP). As already mentioned (Section 7.5), Vas-tenamer is a polymer made by Hulls by ROMP from cyclooctene. Similarly, the polymer from norborene by ROMP is manufactured by CdF Chemie and is sold by the trade name of Norsorex . 

Table IV. French Particleboard Production as a Function of Formaldehyde Emission (% of total Sales by CDF-Chemie).

Ethylene/maleic anhydride Lotrene CdF Chemie Polyamides, ionomers... 

Metathesis of mono- and diolefins can be performed with both homogeneous and heterogeneous catalysis. The most important processes involving metathesis steps, the SHOP process and the Phillips triolefin process, are based on heterogeneous catalysts. Homogeneous catalysts are used in the ring opening metathesis of norbor-nene (Norsorex, CDF-Chemie) and cyclooctene (Vestenamer, Hills) [7]. 

The Centre d Etudes et de Recherches des Phosphates Mineraux (CERPHOS) process was used in a plant of 30,000-tpy capacity in Senegal. It appears to be very similar to the CdF Chemie process except that more extensive purification of the phosphogypsum was used, and this involved wet screening, flotation, two washes, and calcium carbonate addition. The product was dried with heated air in a flash dryer and caldned in an indi-rect-fired kiln. 

Mechanical properties resins - polyester NI423 (CdF Chemie) epoxy LY556/HY951 (Ciba- Geigy) vinyl ester D411-45 (Dow Chemicals). 

There is, however, one further speciality rubber which perhaps should be singled out at this stage. In 1975 the French company CdF Chemie announced the availability of polynorbornene elastomers under the trade name of Norsorex. These materials were quite different from any other rubbers prepared hitherto in that the basic polymer is not itself a rubber. It is a thermoplastic powdery product with a glass transition temperature (Tg) of about +35°C. However, it has a very high compatibility with a large number of aromatic and naphthenic oils and the blends of the polymer with these oils can give rubbers with a very wide range of softness and which may also remain rubbery down to temperatures as low as — 60°C. 

---