Multilamination interdigital mixers

As industrial relevant Friedel-Crafts reaction, the synthesis of Bisphenol-F, a material for epoxy resin, from phenol and formaldehyde was chosen [57]. This reaction involves formation of higher order condensates such as tris-phenols. To minimize the latter, the molar ratio of phenol to formaldehyde is set to a very high value (30-40), which is more than 15 times larger than the amount theoretically necessary. Three types of micromixers were used. These are a T-shaped mixer with 500 pm inner diameter, a multilaminating interdigital micromixer with 40 pm channels and a so-called self-made K-M micromixer with center collision mixing. 

In interdigital multilamination micromixers, the small thickness of the lamellae leads to short diffusion paths, resulting in fast mixing. Further thinning of the liquid lamellae should lead to shorter diffusion paths and faster mixing. The IMM single mixer applied this concept by shrinking the channel width in the slit. A further extension of this concept leads to the... 

The effects of mixing in radical polymerization of MMA are interesting [168]. The use of a 5 mm static mixer leads to fouling in the reactor. In contrast, the use of an interdigital multilamination micromixer with 36 lamellae of 25 pm thickness results in a reduction in fouling. This numbering-up approach enables production of 2,000 tons per year without the fouling problem [169]. 

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