초록 ▼

A method of injection-molding three-layer moldings, especially bottle blanks, having inner and outer layers of a "material A" and of a "material B". Material B can be a material that acts as a barrier against the gases O.sub.2, CO.sub.2, and SO.sub.2, and against water vapor (H.sub.2 O). The method

A method of injection-molding three-layer moldings, especially bottle blanks, having inner and outer layers of a "material A" and of a "material B". Material B can be a material that acts as a barrier against the gases O.sub.2, CO.sub.2, and SO.sub.2, and against water vapor (H.sub.2 O). The method employs a device that comprises at least one mold and at least one flat hot runner. The mold has several cavities and the hot runner has the same number of dies. Material A is supplied to the cavities (1.1) through an annular gap between the inner (2.1) and the outer (2.2) component of each die. Material B is forced into the cavities through a hollow needle (3) that extends through the center of the inner die component by a piston (4) that is integrated into the die and cannot rotate. The needle has a port (6) that opens into it at a right angle and remains open as long as the needle remains advanced, in a closing position, and that is blocked when the needle is retracted. A reservoir (3.3) constituted by the hollow inside the needle is charged through the port while the needle is in its closing position.

대표청구항 ▼

[ We claim:] [1.] Apparatus for injection-molding three-layer moldings with inner and outer layers of a first material and a middle layer of a second material forming a barrier against gases corresponding to O.sub.2, CO.sub.2 and SO.sub.2, and against water vapor; comprising: at least one mold and a

[ We claim:] [1.] Apparatus for injection-molding three-layer moldings with inner and outer layers of a first material and a middle layer of a second material forming a barrier against gases corresponding to O.sub.2, CO.sub.2 and SO.sub.2, and against water vapor; comprising: at least one mold and at least one hot runner plate; said mold having a plurality of cavities; injection die nozzles in said hot runner plate and corresponding in number to said cavities; separate hot-runner systems for supplying said first and second materials to said cavities; each, die nozzle having an inner and an outer component, said first material being supplied through an annular gap between said inner and said outer component; a hollow needle extending through a center of the inner die component by a non-rotatable piston integrated into the die nozzle for forcing said second material into said cavities; said needle having a portion at a right angle to said needle; means for holding said opening open as long as said needle remains advanced in a closing position; means for blocking said opening when said needle is retracted; a reservoir formed by a hollow inside said needle and charged through said port while said needle is in the closing position, said needle sliding back and forth in each die nozzle, said piston sliding back and forth inside said needle and having a longitudinal groove extending as far as said port, said port and said groove allowing said second material to flow out of a supply line and into said reservoir; said port having a position for charging said reservoir only while said needle is advanced in said closing position, said port being blocked as long as said needle is in a retracted position.