Conversion of polyurethane in a tapered reactor

A continuous process for the conversion of a plastic material containing a polyurethane, comprising the following steps:

• providing a reaction mixture, wherein the reaction mixture comprising
• a plastic material in solid form and containing a polyurethane, and further
• an aqueous medium
• wherein in the reaction mixture the mass ratio between the water of the aqueous medium and polyurethane is not more than 0.6 to 1,
• transporting the reaction mixture by means of a first screw conveyor arranged in a first line to a pressure lock formed filling opening of a reactor tapering at least in one end region, relative to the transport direction,
• transporting the reaction mixture by means of a reactor screw conveyor arranged in the reactor vessel at a pressure of >1 bar to 60 bar at a temperature of 180° C. to 270° C. to the end region of the reactor,
• in the end region of the reactor, transferring the reaction mixture thus pressure-treated and heat-treated via a discharge opening designed as a pressure lock into a second line,
• transporting the pressure- and heat-treated reaction mixture by means of a second screw conveyor arranged in the second line,
• providing within the second line an evaporation zone with a temperature which is higher than the temperature prevailing in the reactor,
• in the evaporation zone, removal of gaseous components via at least one degassing point and in or after the evaporation zone, recovery of the reaction mixture which has been pressure- and heat-treated and freed of gaseous components,
• wherein the temperature in the evaporation zone is greater than or equal to the boiling point of nitrogen-containing components and is lower than the boiling point of high-boiling components, and wherein the temperature in the evaporation zone is 265° C. to 300° C.

A continuous process for the conversion of a plastic material containing a polyurethane, comprising the following steps:

• providing a reaction mixture, wherein the reaction mixture comprising
• a plastic material in solid form and containing a polyurethane, and further
• an aqueous medium
• wherein in the reaction mixture the mass ratio between the water of the aqueous medium and polyurethane is not more than 0.6 to 1,
• transporting the reaction mixture by means of a first screw conveyor arranged in a first line to a pressure lock formed filling opening of a reactor tapering at least in one end region, relative to the transport direction,
• transporting the reaction mixture by means of a reactor screw conveyor arranged in the reactor vessel at a pressure of >1 bar to 60 bar at a temperature of 180° C. to 270° C. to the end region of the reactor,
• in the end region of the reactor, transferring the reaction mixture thus pressure-treated and heat-treated via a discharge opening designed as a pressure lock into a second line,
• transporting the pressure- and heat-treated reaction mixture by means of a second screw conveyor arranged in the second line,
• providing within the second line an evaporation zone with a temperature which is higher than the temperature prevailing in the reactor,
• in the evaporation zone, removal of gaseous components via at least one degassing point and in or after the evaporation zone, recovery of the reaction mixture which has been pressure- and heat-treated and freed of gaseous components,
• wherein the temperature in the evaporation zone is greater than or equal to the boiling point of nitrogen-containing components and is lower than the boiling point of high-boiling components, and
• wherein the aqueous medium contains a reaction additive which is selected from nitric acid, a carboxylic acid, a dicarboxylic acid, in particular adipic acid, a tricarboxylic acid, in particular citric acid, and/or urea and/or a biological material.

A continuous process for the conversion of a plastic material containing a polyurethane, comprising the following steps:

• providing a reaction mixture, wherein the reaction mixture comprising
• a plastic material in solid form and containing a polyurethane, and further
• an aqueous medium
• wherein in the reaction mixture the mass ratio between the water of the aqueous medium and polyurethane is not more than 0.6 to 1,
• transporting the reaction mixture by means of a first screw conveyor arranged in a first line to a pressure lock formed filling opening of a reactor tapering at least in one end region, relative to the transport direction,
• transporting the reaction mixture by means of a reactor screw conveyor arranged in the reactor vessel at a pressure of >1 bar to 60 bar at a temperature of 180° C. to 270° C. to the end region of the reactor,
• in the end region of the reactor, transferring the reaction mixture thus pressure-treated and heat-treated via a discharge opening designed as a pressure lock into a second line,
• transporting the pressure- and heat-treated reaction mixture by means of a second screw conveyor arranged in the second line,
• providing within the second line an evaporation zone with a temperature which is higher than the temperature prevailing in the reactor,
• in the evaporation zone, removal of gaseous components via at least one degassing point and in or after the evaporation zone, recovery of the reaction mixture which has been pressure- and heat-treated and freed of gaseous components,
• wherein a dewatering zone is arranged in the second line upstream of the evaporation zone, in which the temperature is above the boiling point of water and below the boiling point of nitrogen-containing components and in which gaseous water can be removed via a water vapor removal point, and
• wherein the aqueous medium contains a reaction additive which is selected from nitric acid, a carboxylic acid, a dicarboxylic acid, in particular adipic acid, a tricarboxylic acid, in particular citric acid, and/or urea and/or a biological material.