Vented twin-screw kneading extrusion apparatus and extrusion method

1. A vented twin-screw kneading extrusion apparatus that discharges organic volatile matter contained in molten resin, the molten resin being obtained by melting and kneading a synthetic resin raw material that is supplied through a raw material supply port on an upstream side of a cylinder constituted by a multiple segment cylinders and is formed from synthetic rubber or from two or more types of polymer including synthetic rubber, to the outside through a vent port in the cylinder, and that extrudes the molten resin from a die provided on a downstream end of the cylinder assembly,

wherein a devolatilization agent, which is injected through a downstream end devolatilization agent injection nozzle provided on a downstream end segment cylinder constituted by a segment cylinder positioned on a downstream end of the cylinder, is dispersed in the molten resin in the downstream end segment cylinder and kneaded by a downstream end kneading portion such that the molten resin is foamed by the devolatilization agent and then extruded.

2. The vented twin-screw kneading extrusion apparatus according to claim 1 , wherein a multiple devolatilization agent injection nozzles, a multiple vent ports, and a multiple kneading portions are provided between the raw material supply port and the downstream end segment cylinder of the cylinder assembly.

3. The vented twin-screw kneading extrusion apparatus according to claim 2 , wherein a cylinder temperature of the downstream end segment cylinder is set to be equal to or higher than a boiling point of the devolatilization agent and lower than a limit heat resistance temperature of the synthetic rubber.

4. The vented twin-screw kneading extrusion apparatus according to claim 2 , wherein the devolatilization agent is injected at a ratio of 1.0% to 15% relative to the molten resin, and

a back pressure on an upstream side of the die equals or exceeds a vapor pressure of the devolatilization agent at the limit heat resistance temperature of the synthetic rubber.

5. The vented twin-screw kneading extrusion apparatus according to claim 2 , wherein the synthetic resin raw material is formed from a mixture of synthetic rubber and an organic solvent, and

the devolatilization agent is formed from water.

6. The vented twin-screw kneading extrusion apparatus according to claim 2 , wherein the die is constituted by a die having a pressure adjustment mechanism.

7. The vented twin-screw kneading extrusion apparatus according to claim 1 , wherein one of water, nitrogen, and carbon dioxide is used as the devolatilization agent.

8. The vented twin-screw kneading extrusion apparatus according to claim 7 , wherein a cylinder temperature of the downstream end segment cylinder is set to be equal to or higher than a boiling point of the devolatilization agent and lower than a limit heat resistance temperature of the synthetic rubber.

9. The vented twin-screw kneading extrusion apparatus according to claim 7 , wherein the devolatilization agent is injected at a ratio of 1.0% to 15% relative to the molten resin, and

a back pressure on an upstream side of the die equals or exceeds a vapor pressure of the devolatilization agent at the limit heat resistance temperature of the synthetic rubber.

10. The vented twin-screw kneading extrusion apparatus according to claim 7 , wherein the die is constituted by a die having a pressure adjustment mechanism.

11. The vented twin-screw kneading extrusion apparatus according to claim 1 , wherein a cylinder temperature of the downstream end segment cylinder is set to be equal to or higher than a boiling point of the devolatilization agent and lower than a limit heat resistance temperature of the synthetic rubber.

12. The vented twin-screw kneading extrusion apparatus according to claim 11 , wherein the devolatilization agent is injected at a ratio of 1.0% to 15% relative to the molten resin, and

a back pressure on an upstream side of the die equals or exceeds a vapor pressure of the devolatilization agent at the limit heat resistance temperature of the synthetic rubber.

13. The vented twin-screw kneading extrusion apparatus according to claim 11 , wherein the synthetic resin raw material is formed from a mixture of synthetic rubber and an organic solvent, and

the devolatilization agent is formed from water.

14. The vented twin-screw kneading extrusion apparatus according to claim 11 , wherein the die is constituted by a die having a pressure adjustment mechanism.

15. The vented twin-screw kneading extrusion apparatus according to claim 1 , wherein the devolatilization agent is injected at a ratio of 1.0% to 15% relative to the molten resin, and

a back pressure on an upstream side of the die equals or exceeds a vapor pressure of the devolatilization agent at the limit heat resistance temperature of the synthetic rubber.

16. The vented twin-screw kneading extrusion apparatus according to claim 15 , wherein the synthetic resin raw material is formed from a mixture of synthetic rubber and an organic solvent, and

the devolatilization agent is formed from water.

17. The vented twin-screw kneading extrusion apparatus according to claim 15 , wherein the die is constituted by a die having a pressure adjustment mechanism.

18. The vented twin-screw kneading extrusion apparatus according to claim 1 , wherein the synthetic resin raw material is formed from a mixture of synthetic rubber and an organic solvent, and

the devolatilization agent is formed from water.

19. The vented twin-screw kneading extrusion apparatus according to claim 1 , wherein one of water, nitrogen, and carbon dioxide is used as the devolatilization agent.

20. The vented twin-screw kneading extrusion apparatus according to claim 18 , wherein the die is constituted by a die having a pressure adjustment mechanism.

21. The vented twin-screw kneading extrusion apparatus according to claim 1 , wherein the die is constituted by a die having a pressure adjustment mechanism.