Injection physical foaming inner boot and method of manufacturing inner boot by injection physical foaming

An injection physical foaming inner boot, comprising:

• a foot portion, comprising a forefoot section and a hindfoot section, wherein a hardness of the forefoot section is greater than a hardness of the hindfoot section;
• and
• a shaft portion, extending upwards from the hindfoot section of the foot portion, wherein the foot portion and the shaft portion are integrally formed;
• both the foot portion and the shaft portion include a thermoplastic material and do not include a crosslinking agent and a chemical foaming agent;
• both a specific gravity of the foot portion and a specific gravity of the shaft portion range between 0.1 g/cm3 and 0.3 g/cm3;
• the hardness of the forefoot section is greater than a hardness of the shaft portion;
• an inner layer, wherein the inner layer comprises an inner foot section and an inner shaft section;
• the inner foot section is correspondingly engaged with an inner surface of the foot portion;
• the inner shaft section is correspondingly engaged with an inner surface of the shaft portion, wherein an extensible region and an inextensible region are defined on the inner layer;
• the extensible region is distributed on a part of the inner shaft section and a part of the inner foot section, the inextensible region is distributed on another part of the inner shaft section and another part of the inner foot section;
• an area of the inextensible region of the inner shaft section is less than an area of the extensible region of the inner shaft section;
• an area of the inextensible region of the inner foot section is less than an area of the extensible region of the inner foot section;
• the inextensible region of the inner shaft section is larger than the inextensible region of the inner foot section;
• and
• at least one reinforcement member disposed on an outer surface of at least one of the shaft portion or the foot portion, when the at least one reinforcement member is fixed on the outer surface of the shaft portion, the at least one reinforcement member is fixed on the shaft portion through sewing and is engaged with the inextensible region of the inner layer;
• when the at least one reinforcement member is fixed on the outer surface of the foot portion, the at least one reinforcement member is fixed on the foot portion through sewing and is engaged with the inextensible region of the inner layer.