MOULDED PRODUCT OF THERMOPLASTIC AND METHOD FOR ITS MANUFACTURE Russian patent published in 2000 - IPC

FIELD: moulded products of thermoplastic, films of foam plastic. SUBSTANCE: one film surface is closed, and the other, at least partially, is open so that the open pores that are contiguous to this surface are accessible for liquid. The moulded product contains at least 10 volume percent of open pores. The pores have a polyhedron shape with mechanically undistorted walls and adjoin one another. At least two walls of each individual pore have a hole at preservation of the mechanical strength of the space matrix that accommodates the open pores. The walls of the pores surrounding the holes are mechanically undistorted. In the method for manufacture of moulded product produced is a melt of at least one base polymer and a structure forming agent in the first stage of extrusion, blowing agent is introduced, and homogeneous mixing of it with the polymer melt is accomplished at the end of the first stage of extrusion. The melt is obtained at a temperature of 300 C. The blowing agent is introduced in the polymer melt by injection of it at a high pressure up to 350 bars. In the second stage of extrusion, just before extrusion, the polymer melt is cooled down to a temperature of 120-250 C. At least one of the closed surfaces of extruded thermoplastic material gets partially open by grinding, scratching, perforation or cooling and simultaneous tension at the outlet from the die. Holes are made at least in two walls of each open pore. EFFECT: manufacture of moulded product of foam plastic with an open cellular structure, changing within a wide range, the pore are permeable for agents without mechanical distortion of pore walls. 31 cl, 6 dwg