Patent ID: 7778754

Claim:
A method of preventing mixing of materials in two-shot molding where a cavity is formed in an injection mold for production of a crash pad, suitable for integral formation of a passenger-side airbag door region made of a second material having high softness and portions of the crash pad other than the passenger-side airbag door region, made of a first material having high hardness, through two-shot molding, to produce the crash pad, the method comprising: forming a flow-retarding dam at a portion of the cavity in the injection mold which is positioned outside the passenger-side airbag door region, wherein the cavity includes a first part and a second part divided by the flow-retarding dam, injecting the second material into the second part of the cavity that corresponds to the passenger-side airbag door region; and injecting the first material into the first part of the cavity that corresponds to other than the passenger-side airbag door region, wherein the injecting of the first material into the first part of the cavity and the second material into the second part of the cavity is performed simultaneously; and wherein a thickness of a predetermined portion of the crash pad that is made by the flow-retarding dam, by which the first part of the cavity and the second part of the cavity are divided, is decreased, and thus retarding flow of the first material in the predetermined portion and promoting solidification of the first material in the redetermined portion is accomplished.