Die, method of manufacturing die, extruder and method of manufacturing pellet

A die having an extrusion surface and an injection surface opposite to the extrusion surface, comprising:

• a first member made of a first metallic material;
• an injection hole formed from a first surface of the first member into the first member, the first surface of the first member being closer to the injection surface than the extrusion surface;
• a first nozzle formed inside the first member and connected to the injection hole;
• a second nozzle formed from a second surface of the first member into the first member, the second surface of the first member being closer to the extrusion surface than the injection surface, connected to the first nozzle, and having a smaller average opening diameter than an average opening diameter of the first nozzle;
• and
• a first heat source arranged inside the first member not to overlap the first nozzle and the second nozzle in a plan view viewed from the extrusion surface,
• wherein a plurality of first holes are formed inside the first member so as to be away from the first heat source, each of the plurality of first holes having an annular shape in the plan view and being formed as an enclosed space filled with air or an inert gas, the plurality of first holes forming first heat insulating layers having a lower thermal conductivity than a thermal conductivity of the first metallic material,
• one of the plurality of first holes is adjacent to the second nozzle and is closer to the extrusion surface than the first heat source,
• the other of the plurality of first holes extends in a direction from the extrusion surface toward the injection surface at a position that is farther from the second nozzle than the first heat source.