EVA melt gear pump

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EVA resin usage

EVA is a copolymer of LLDPE (linear low density polyethylene) and acetic acid (VA). It is an ethylene vinyl acetate copolymer, which is prepared by copolymerization of ethylene (E) and vinyl acetate (VA). Its English name is Ethylene Vinyl Acetate, abbreviated as EVA, or E/VAC. The structural formula is: (CH2CH-0H) n.

EVA resin

EVA resin has a wide range of uses. In general, EVA with a vinyl acetate content of less than 5% mainly produces films, wires and cables, LDPE modifiers, adhesives, etc; EVA products with a vinyl acetate content of 5% -10% are elastic films, etc; EVA with a vinyl acetate content of 20-28% is mainly used for hot melt adhesives and coating products; The content of vinyl acetate is between 5% and 45%, and the main products are films (including agricultural films) and sheets, injection molded and molded products, foam products, hot melt adhesives, etc.

Design of EVA specific thermoplastic melt pump

The design of EVA specialized extrusion melt pump is optimized based on its processing process. Mainly reflected in the following points:

1. The temperature control is electric heating+circulating water temperature regulation.

EVA modified adhesive resin must have sufficient time to activate the anhydride during co extrusion to ensure sufficient adhesion. Therefore, setting the temperature is very important. To prevent EVA from degrading due to excessive processing temperature, the processing temperature should be limited to 238 degrees. The internal design of the EVA specialized melt pump is equipped with circulating temperature control water for temperature regulation.

2. The design of the flow channel has no dead corners, and the internal circulation flow channel has a smooth arc transition.

Excessive temperature or dead corners during the extrusion process can cause the retention time of EVA resin to be too long, which may cause resin aging. Therefore, the retention time also affects the quality of the film. The design concept of the EVA melt gear pump is similar to that of the rubber melt pump, which has no dead corners inside and a uniform and smooth transition of the circulating lubrication channel.

3. Gear shaft temperature controlled circulating water.

When the gear mesh is used to transport resin adhesive, it will generate shear heat. To avoid rapid temperature rise, the shaft of the EVA melt pump is designed with circulating temperature controlled water, and the shaft head is equipped with a rotating joint.

4. Adopting a helical tooth design.

The gears of the EVA melt gear pump adopt helical meshing, and the meshing operation is stable. The production capacity increases and the shear effect decreases.

5. The seal is a maintenance free spiral seal.

The EVA melt pump adopts a spiral sealing form to avoid the impact of residue from conventional packing sealing on the product.

EVA melt pump