The special material sheet extruder is a device specially used to process polymer materials or composite materials into thin sheet products. Its operating principle is similar to that of ordinary plastic extruders, but in order to adapt to the characteristics of special materials (such as high-temperature materials, optical materials, conductive materials, biodegradable materials, etc.), it has been strengthened and improved in design and process control.
I. Basic principle
Raw material supply
The raw material (usually granular, powder or liquid) enters the extruder hopper through an automatic feeding system.
Heating and melting
After the raw material enters the barrel, it is gradually heated and melted under the shearing action of the screw rotation.
For special materials, the barrel requires a higher precision temperature control system (multi-zone temperature control) to ensure that the heat-sensitive properties of the material are not destroyed.
Plasticization and mixing
The screw further compresses, mixes and plasticizes the material to make the melt have good uniformity.
Some special materials require special screw structures (such as barrier screws, mixing sections) to improve dispersion or prevent degradation.
Extrusion molding
The melt is extruded from the extruder head (die) in the shape of a sheet, and the die mouth is usually a flat die head.
The die head needs to have good pressure balance and precise flow channel design to ensure uniform sheet thickness.
Cooling and shaping
The extruded sheet is cooled, shaped and flattened by a three-roll calender (calender roller group).
Hot pressing or cold pressing can be selected according to the material properties, and sometimes used in conjunction with a vacuum shaping device.
Tractive and winding
After the sheet is cooled, it is continuously and stably pulled out by the tractor and wound into a roll, or cut into sheets and stacked.
2. Special design and function
For "special materials", the extruder system usually has the following features:
Special requirements
Design that can meet various needs
High temperature materials (such as PEEK, PTFE)
High temperature alloy barrel, high temperature resistant seal, 600°C heating system
Optical sheet (such as PC optical film)
High cleanliness, low shear design, pollution-free process
Conductive sheet
Multiple mixing sections, precise proportioning system
Biodegradable materials (such as PLA, PHA)
Precise temperature control, low shear anti-degradation design
Multi-layer co-extrusion
Multiple extruders co-extrusion die head
3. Application areas
Medical sheet (biodegradable or antibacterial sheet)
Optical display materials (LCD diffuser, light guide)
Food packaging materials (degradable plastic sheet)
High temperature engineering materials (electronic packaging sheet, heat-resistant structural sheet)
Electromagnetic shielding materials (conductive carbon fiber sheet)
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