Method of forming closed cell foam seals for automotive body seams

A method of sealing automotive body seams comprising

• supplying a controlled amount of foamable liquid polymeric sealant material from a bulk reservoir through a mixer for mixing said sealant material with a gas to a dispensing nozzle, said mixer having a housing with an inlet for receiving said polymeric material and an outlet for dispensing said polymeric material,
• introducing said gas under pressure into said mixer for solubilization in said polymeric material,
• providing a laminar flow of said polymeric material through said mixer to increase dissolution of said gas into said polymeric material to form a polymer/gas solution under pressure,
• maintaining said gas in solution with said polymeric material in said mixer,
• dispensing the polymer/gas solution downstream of said mixer outlet with a low pressure drop across said mixer inlet to said outlet thereby avoiding premature foaming of said polymeric material in said mixer whereby said gas is released at atmospheric pressure from solution forming a polymer sealant foam,
• forming directly in place a bead of said polymer sealant foam from said nozzle into an automobile body seam,
• controlling said bead to a desired width and amount as the foam expands to fill the seam,
• and curing said polymer sealant foam thereby providing in said seam a seal having a closed cell foam structure with a multitude of fine cells containing gas, thereby sealing said automotive body against moisture, dust and noise intrusion.