Seat moulding procedure, esp. for orthopaedic seat for handicapped person - uses rigid shell covered by supple film layer and filled with expanding and solidifying foam

摘要

The procedure consists of covering a rigid shell (1) with a layer of a supple elastic and/or plastic film, and drawing it against the inner walls of the shell with the aid of a vacuum. Then, after the user has been placed in position on the seat an expanding and solidifying foam is injected between the shell and the covering film, adapting to the shape of the user's body. This initial shape is then used as a basis for making positive and negative impressions. The supple film layer has a thickness of between 25 and 50 mu m, a stretch module of 4.9 MPa, and a resistance to traction of 27.6 MPa. The expanding foam is a mixture based on diphenylmethane-1,4-diisocyanate, while a second foam, which is a mixture of toluene diisocyanate-2,4 (80 per cent) and toluene diisocyanate-2.6 (20 per cent), is used for making the positive and negative impressions.