Seal gasket element for a mixing apparatus, method for obtaining and applying the same, and special equipment for fitting the same

High-pressure mixing apparatus for polymer components that are suitable for forming a chemically reactive mixture, comprising:

• a base body defining internally a mixing chamber that is suitable for receiving, by respective injection openings or nozzles, jets of said reactive polymer components,
• a slide valve member having a stem portion extending with a longitudinal axis and connected behind to a piston drive portion, on said stem portion two or more longitudinal slots being obtained for recirculating polymer components,
• said slide valve member being reciprocal in said mixing chamber between a retracted open position, which enables jets to be mixed by turbulence in the mixing chamber, and the subsequent dispensing of said mixture, and an advanced position for expelling residual reactant residues to a mould and closing said mixing chamber, in which advanced position said jet injection openings are placed in communication by said longitudinal recirculation slots with respective recirculating openings made on said body,
• WHEREIN said slide valve member stem portion has a cylindrical surface suitable for coupling with the cylindrical surface of said mixing chamber in which said slide valve member is slidable with preset clearance, said stem portion cylindrical surface containing housing seats formed with a grid shape such as to surround, without intersecting and without discontinuity, said longitudinal recirculation slots;
• a seal gasket element obtained from a precursor element made of an elastoplastic material separately from said slide valve member, said seal gasket element being further provided with longitudinal seal portions, parallel to said longitudinal axis, and transverse seal portions that extend circumferentially around said longitudinal axis, said seal gasket element being coupled with said slide valve member and being formed with a grid structure with a reticular shape corresponding to that of said housing seats, said longitudinal seal portions and transverse seal portions having enlarged sections with respect to the respective housing seats, the enlarged sections are housed with forced positioning in the respective housing seats on said stem portion cylindrical surface and being configured for exerting pressure on the surface on which they slide so as to avoid a leak of polymer components from a said longitudinal slot to another said longitudinal slot and avoid a leak of reactant mixture from said mixing chamber to the recirculation slots of said slide valve member when the resins are dispensed into the mould.