Apparatus and method for multi-layer injection molding

An injection molding apparatus for multi-layer molding comprising:

• a nozzle having a central bore;
• a central melt channel having a first portion for flow of a first material, a second portion for flow of the first material and a second material, and a flow extension connecting the first portion and the second portion, at least a part of the second portion being defined by the central bore of the nozzle, the flow extension having a flow opening positioned before the central bore of the nozzle;
• an annular ring channel around the central melt channel for flow of the second material, the annular ring channel being in connection with the flow opening of the flow extension;
• and
• an annular melt channel for flow of the first material, the annular melt channel being in connection with the central melt channel, at least a portion of the annular melt channel being positioned within the nozzle and in communication with a front opening in the nozzle, the annular melt channel being in communication with the central melt channel near the front opening in the nozzle;
• wherein the first and second materials flow together through the entire central bore of the nozzle.

An injection molding apparatus for multi-layer molding comprising

• a nozzle having a central melt channel and an annular melt channel radially spaced from the central melt channel;
• a first manifold to guide a first material toward the nozzle;
• a first melt passage positioned within the first manifold for flow of the first material, the first melt passage being split within the first manifold into a first melt branch and a second melt branch, the first melt branch being in connection with the central melt channel, and the second melt branch being in connection with the annular melt channel;
• a second manifold to guide a second material toward the nozzle;
• and
• a second melt passage positioned within the second manifold for flow of the second material, the second melt passage being in connection with the central melt channel.