Patent ID: 7115671

Claim:
Process for recovering monomeric units of a nylon from carpet material, said carpet material comprising fibres containing said nylon bound to a backing containing one or more non-nylon components, the carpet material containing between 15 and 35 wt. % of said nylon, which process comprises the steps of: a) mechanically separating the carpet material into an enriched carpet mixture containing between 35 and 55 wt. % of said nylon and into a depleted carpet mixture having a lower content of said nylon than the carpet material, by a1) mechanically treating the carpet material ( 1 ), using a shredder with knives, the knives being sufficiently blunt so as to size reduce the backing and to loosen at least 15 wt. % of the fibres from the backing, resulting in a primary loosened carpet mixture ( 2 ) comprising backing particles and fibres; and a2) sieving the primary loosened carpet mixture ( 2 ) to obtain said enriched carpet mixture ( 3 ) and said depleted carpet mixture ( 4 ), the enriched carpet mixture having in the range between 35 and 55 wt % nylon, which is a higher content of said nylon than the nylon content in the primary loosened carpet mixture, the depleted carpet mixture having a lower content of said nylon than the primary loosened carpet mixture, whereby the viscosity of the enriched carpet mixture is decreased at the conditions at which depolymerization is effected, whereby the sieving yield, which is the total mass of the desired nylon in the enriched carpet mixture divided by the total mass of nylon in the primary loosened carpet mixture prior to sieving is increased over the range of 35 and 55 wt % nylon in the enriched carpet mixture; and b) exposing the enriched carpet mixture to conditions at which depolymerisation of said nylon is effected.