A method for injection molding of a continuous, three-dimensional web-shaped product of thermoplastic material.

摘要

1,237,746. Continuous injection moulding. MONSANTO CO. 28 June, 1968 [3 July, 1967], No. 31022/68. Heading B5A. [Also in Division A4] Articles, e.g. artificial turf, ski-slopes &c. having a matrix and projections, are produced by injection moulding into cavities in a moving mould surface at a first pressure to form the projections and then across the face of the mould surface at a lower pressure to form the matrix integral with the projections. The mould surface may be a cylindrical drum 14, Figs. 2, 3, on surfaces of abutting flat plates (Figs. 10, 11, not shown), between two rotating cylindrical drums (Figs. 12-14, not shown) or between a rotating drum and the nozzle face (Figs. 18, 19, not shown). As shown in Figs. 2, 3, material is injected into cavities 34 having inserts 36 and closed from grooves 44 on drum 14 by extruder fingers 42. As the drum rotates, material is injected at a lower pressure into grooves 44 between fingers 42 and portions 40 on the drum. Longitudinal recesses 38 in inserts 36 form the projections. The product (Fig. 8, not shown) may be textured (as Fig. 9, not shown) to have a grass-like appearance. The drum 14 may be water-cooled; the product is stripped therefrom by means 34. In an alternative embodiment (Figs. 10, 11, not shown), plates (70) are abutted to form the mould, being removed from the product after moulding and recycled. Recesses (74) form the projections, being closed from grooves (78) by fingers (77). In the embodiment of Figs. 12-14 (not shown), one rotating drum (90) contains cavities (92) for the projections, and another drum (96) the grooves. Injection nozzle (A) operates at high pressure into cavities (92) and (B) at lower pressure into the grooves, fingers (106) preventing back flow. Nozzles (A, B) are both connected to source (102), (B) having a valve (104) to lower the injection pressure. Two rows of extruders (Figs. 15-17, not shown) may be used, one row operating at a different pressure to the other. In Figs. 18-20 (not shown), grooves (120) are formed in the nozzle face, injection being effected through (F) at low pressure due to valve (134), and through (E) at higher pressure to form the projections. The drums (Figs. 21, 22, not shown) may have T-shaped transverse grooves (140) to form the projections and circumferential grooves (142) to form the matrix (150).