Patent ID: 8298652

Claim:
A resin molded large-sized product having an opening and an appearance surface, the resin molded product being produced by an injection molding method using an injection molding die, the injection molding die comprising: a movable die member provided with a molded product's appearance surface forming portion; and a fixed die member provided with a molded product's rear surface forming portion, the fixed die member being provided with two or more hot runners to provide two or more resin supplying paths, the fixed die member being provided with two or more gates each connected to a hot runner from which a molten resin is injected into a cavity defined by the molded product's appearance surface forming portion and the molded product's rear surface forming portion; the two or more gates being one or more direct valve gates directly opening from the fixed die member to the cavity and opened/closed by a valve, the two or more direct valve gates being disposed in the molded product's rear surface forming portion; and the movable die member or each of the movable die member and the fixed die member being integrally provided with a protrusion for making said opening so as to use no insert, the injection molding method comprising steps of: heating a vicinity of the molded product's appearance surface forming portion of the die to a temperature higher by 10° C. to 100° C. than a deflection temperature under load of a resin to be used; injecting a molten resin from the two or more gates each connected to a hot runner into the die integrally provided with a protrusion which makes said opening and without using an insert; and cooling the vicinity of the molded product's appearance surface forming portion of the die to a temperature lower by 0° C. to 100° C. than a deflection temperature under load of the resin used to bring the resulting resin molded product into such a condition that the resin molded product can be removed from the die, wherein the appearance surface of the molded product thus produced is lustrous and has a mirror-like smooth surface that has been transferred from the molded product's appearance surface forming portion.