2014 Archive

The recycle of PP woven bag

1 discussed here is "" bags of recycling, waste is suitable for production" "" "plastic trash bags. This is the recycling of a single variety, demand is higher, cannot be mixed with other varieties of plastic, more not contain sand, sundry, mechanical impurities, etc., the requirements of the melt index in the range of 2-5 any pp plastic (not available).Its source mainly has two, one is "" bag of the waste in the process of production; Second, scrap recycling pp bag products, such as fertilizer bags, feed bags, salt bag, etc.

2 regeneration methods

It mainly has fused aggregate method and extrusion granulation method two, most of the extrusion granulation method is used.  Process of the two methods are as follows.

2.1 melting granule

Waste material and water - dry - cut article - the aggregate charge - thermal contraction - water - (aggregate) the packing material.

2.2 extrusion granulation method

Waste - material - water - air - article cut - heating extrusion - cooling pelletizing - packing.
Extrusion method used equipment is made of the secondary type extruder, to eliminate waste gas generated in extrusion, exhaust type extruder is also available. To eliminate the waste of the stuff in the extruder discharging end must be 80-120 mesh screen.

3. Reworked material used and the effect on the properties of pp bag because of the plastic processing of thermal aging on performance when influential, especially "" recycling bag after two thermal process for many times, even before and recycling use of ultraviolet radiation ageing, the performance has significantly decreased.

4. The use of reworked material to the adjustment of the drawing technology for pp plastic hot working many times produce thermal aging and ultraviolet radiation aging in long-term use, the melt index of pp recycled material along with the increasing processing times higher (see chart 2).Therefore, within the new material added to recycle material, in the process of temperature control, a relatively new material, the extruder temperature, head temperature, stretching should be recalibrated, finalize the design temperature adjustment amount by testing the melt index of the old and the new mixture.

As recycling material, on the other hand, after many processing, lower molecular weight, there are a lot of short chain, and after a lot of stretch orientation. Therefore, in the process of production, draw ratio is relatively the same new material down. New material commonly draw ratio is 4-5 times, after the addition of 40% recycled material is commonly 3 -- 4 times. Also due to the progress of material melt index, reduced viscosity, extrusion rate improved, so the same screw rotation speed and temperature conditions, the drawing of the traction speed also to speed up slightly. In the mixing of new and old materials, keep in mind to the mix;  Should choose as far as possible at the same time melt index of similar raw materials to match. Melt index difference is big, the molten temperature difference is big. In plasticizing extruder, two kinds of materials can't plasticizing at the same time, will seriously affect the extrusion tensile speed, causing high rejection rate, even unable to production.