Method for producing a molded part and molded part

A method for producing a shoe sole, comprising:

• providing a mixture of a polymer melt and a foaming agent;
• injecting the mixture into a mold, wherein the mold comprises at least a first section corresponding to a first portion of the shoe sole and at least a second section corresponding to a second portion of the shoe sole fluidly connected to the first section, wherein the first portion and the second portion each include a top surface and a bottom surface of the shoe sole;
• and
• solidifying at least the first portion of the shoe sole without foaming and at least a second portion of the shoe sole with foaming by increasing the volume of one of the first section and the second section to induce foaming of the mixture in the one of the first section and the second section while not changing the volume of the other of the first section and the second section such that one of the first portion of the shoe sole and the second portion of the shoe sole has a desired mechanical property, wherein the first portion and the second portion form a single integrated shoe sole, and
• wherein the mixture comprises a polymer having an average molecular mass corresponding to a viscosity number ≥130 ml/g, wherein the viscosity number is determined via solution viscometry according to the ISO 307 standard.

A method for producing a molded shoe sole, comprising:

• providing a mixture of a polymer melt and a foaming agent;
• injecting the mixture into a mold of the shoe sole, wherein the mold comprises a heel section, a midfoot section, and a forefoot section;
• and
• solidifying the forefoot section of the shoe sole without foaming;
• controlling the foaming between the foamed midfoot section and the unfoamed forefoot section to form a transition zone where the material of the sole continuously transitions from a foamed material to an unfoamed material between the midfoot section and the forefoot section;
• solidifying at least one of the midfoot section and the heel section with foaming, wherein the unfoamed forefoot section of the sole is more flexible than the foamed midfoot section or heel section because the forefoot section is unfoamed, wherein the forefoot section, heel section, and midfoot section form a single integrated shoe sole.