Process for making high performance pressure sensitive adhesive tapes

A process for producing sheets of curable pressure sensitive adhesive material, said process comprising:

• providing a twin screw extruder having at least one upstream feed unit and at least one downstream solvent removal unit, said solvent removal unit comprising a barrel section having a large vent opening, a vacuum pump, and a duct surrounding the vent opening and extending from the barrel section to the vacuum pump whereby the vacuum pump can be activated to reduce the pressure within the barrel section, vent opening and duct;
• introducing into the feed unit of the extruder an adhesive composition comprising a curable pressure sensitive adhesive polymer matrix and a solvent for the pressure sensitive adhesive polymer matrix, said solvent being present in an amount of from about 20% to about 60% by volume of the adhesive composition;
• conveying the composition through the extruder;
• heating the adhesive composition to a temperature of from about 8.degree. C. to about 160.degree. C. as it is conveyed through the extruder;
• section;
• and
• activating the vacuum pump to reduce the pressure in the barrel section of the solvent removal unit sufficientyl to evaporate at least a portion of the solvent in the adhesive composition conveyed through that section;
• and
• extruding curable pressure sensitive adhesive material through a sheet die onto a backing film to provide a uniform coating of pressure sensitive adhesive on the backing film.

A process for coating curable solution polymerized pressure sensitive adhesive material onto a backing film, said process comprising:

• introducing into an extruder through a feed unit a pressure sensitive adhesive composition comprising a curable pressure sensitive adhesive polymer matrix and solvent for the pressure sensitive adhesive matrix, the solvent being present in the composition in an amount of from about 20% to about 60% by volume of the composition, said composition is at a temperature less than the boiling point of the solvent in the composition;
• conveying the adhesive composition through the extruder;
• heating the adhesive composition to a temperature of from about 80.degree. C. to about 160.degree. C. as it is conveyed through the extruder;
• reducing the pressure in at least one section of the extruder sufficiently to evaporate at least a portion of the solvent in the pressure sensitive adhesive composition conveyed through the section;
• removing the evaporated solvent from the extruder;
• and
• extruding a solvent-free curable adhesive material as a uniform coating onto a backing film.

A process for coating curable pressure sensitive adhesive material onto a backing film, said process comprising:

• introducing into an extruder through a feed unit a pressure sensitive adhesive composition comprising a curable pressure sensitive adhesive polymer matrix and solvent for the pressure sensitive adhesive matrix, said solvent being present in the composition in an amount of from about 20% to about 60% by volume of the composition;
• conveying the adhesive composition through the extruder;
• heating the adhesive composition to a temperature of from about 80.degree. C. to a temperature below the degradation temperature of the adhesive composition as it is conveyed through the extruder;
• reducing the pressure in at least one section of the extruder sufficiently to evaporate at least a portion of the solvent in the pressure sensitive adhesive composition conveyed through that section;
• removing the evaporated solvent from the extruder;
• and
• extruding solvent-reduced curable pressure sensitive adhesive material onto a backing film to thereby provide a uniform coating of pressure sensitive adhesive on the backing film.