Resin injection molding method

A method for molding resins inside a cavity formed within a mold, the method comprising:

• heating the mold to a temperature equal to or higher than a melting temperature of the resin before opening a plurality of paths installed so as to be openable and closable and optionally maintaining the resin inside the cavity at a pressure;
• injecting resins into the cavity through the plurality of paths;
• closing each of the plurality of paths such that the resins injected from each path converge, there being a time difference between when a first path of the plurality of paths is injected the resin and optionally maintained the resin inside the cavity at pressure which is completed maintaining at pressure and a second path of the plurality of paths is injected the resin and optionally maintained the resin inside the cavity at pressure which is completed maintaining at pressure, by which the resin which has been injected from the first path submerges into the resin which has been injected from the second path;
• and
• cooling the mold so as to control solidification of at least the resin being injected from the path at which injecting the resin and optionally maintaining the resin inside the cavity at pressure which is completed maintaining at pressure earliest, wherein the resin has a crystallinity degree of 20% or more after cooling,
• wherein closing the paths comprises the steps of:
• completing maintenance of the resin from the second path at pressure by closing the second path,
• solidifying the resin while the resin from the first path is maintained at pressure, and
• completing the maintenance of the resin from the first path at pressure by closing the first path after the temperature of the mold falls to a temperature lower than or equal to a heat distortion temperature of the resin.

A method for molding resins inside a cavity formed within a mold, the method comprising:

• heating the mold to a temperature equal to or higher than a melting temperature of the resin before opening a plurality of paths installed so as to be openable and closable and optionally maintaining the resin inside the cavity at a pressure;
• injecting resins into the cavity through the plurality of paths;
• closing each of the plurality of paths such that the resins injected from each path converge, there being a pressure difference between in a first path being maintained the resin at a pressure value and a second path being maintained the resin at a pressure value, by which the resin from the first path maintained in higher pressure value submerges into the resin from the second path maintained in lower pressure value;
• and
• cooling the mold so as to control solidification of at least the resin being injected from the path maintained at a lowest pressure value, wherein the resin has a crystallinity degree of 20% or more after cooling,
• wherein closing the paths comprises the steps of:
• completing maintenance of the resin from the second path at pressure,
• solidifying the resin while the resin from the first path is continuously maintained at the pressure value until the temperature of the mold falls to a temperature lower than or equal to a heat distortion temperature of the resin, and then
• closing both the first and second paths.