Patent ID: 8727761

Claim:
A die for underwater cutting type pelletizer to be used in an underwater cutting type pelletizer for making pellets from a thermoplastic resin derived from a mixer/extruder, the die comprising: an annular die orifice part having a plurality of die orifices for allowing the thermoplastic resin to pass through; an outer periphery-side fixing part provided on the outer periphery side of said die orifice part to fix said die orifice part to the mixer/extruder; an inner periphery-side fixing part provided on the inner periphery side of said die orifice part and having at least one fixing element configured to fix said die orifice part to the mixer/extruder; an outside annular passage formed within at least one of said die orifice part and said outer periphery-side fixing part along a boundary line between said die orifice part and said outer periphery-side fixing part; an inside annular passage formed within at least one of said die orifice part and said inner periphery-side fixing part along a boundary line between said die orifice part and said inner periphery-side fixing part; a communicating passage formed in an area other than the area where each die orifice is formed within said die orifice part to allow said outside annular passage to communicate with said inside annular passage, thereby circulating heated fluid to said outside annular passage and said inside annular passage to heat said die orifice part; and a heating part provided within said inner periphery-side fixing part along said inside annular passage, and positioned closer to the inner periphery side than said at least one fixing element, to heat said inner periphery-side fixing part and to minimize a temperature difference between the die orifice part and the inner periphery-side fixing part.