1 The discussion here is "" recycling of bags, waste refers to "plastic waste" suitable for the production of "" bags. This is a single type of waste utilization, the requirements are relatively high, can not be mixed with other varieties of plastic, can not contain sediment, debris, mechanical impurities, etc., its melt index is required to be in the range of 2--5 (not any Pp plastics are available). There are two main sources, one is "the waste in the bag production process; the second is the recycling of discarded pp bags, such as fertilizer bags, feed bags, salt bags and so on. Linen Cotton Fabric,Sailing Vessel Fabri,Wash Painting Pattern Fabric,Dark Blue Fabric Shaoxing City Jiaren Textile Co., ltd. , https://www.jiarentextile.com
2 regeneration method
It mainly has two kinds of molten pellet method and extrusion granulation method, and most of them adopt extrusion granulation method. The flow of the two methods is as follows.
2.1 molten pellet method
Waste - material selection and washing - drying - cutting - high-speed pellets (feeding - heat shrinking - spray - pellets) discharge packaging.
2.2 Extrusion granulation method
Waste - selection of materials - washing - drying - cutting - heating extrusion - cooling pellets - packaging.
The equipment used in the extrusion process is a self-made two-stage extruder. To exclude the gas generated in the extrusion of the waste, a vented extruder can also be used. In order to eliminate the debris in the waste, a screen of 80-120 mesh must be used at the discharge end of the extruder.
3. The use of recycled materials and the impact on the performance of pp bags due to the thermal aging of plastic processing has a considerable impact on performance, especially the recycling of "" bags after two or even multiple thermal processes, plus in use before recycling The UV aging has a significant decrease in performance.
4. Recycling of raw materials The adjustment of the drawing process is caused by heat aging of pp plastics and heat aging during long-term use, resulting in an increase in the melt index of pp regrind as the number of processing increases (see Table 2). . Therefore, after adding a large amount of recycled materials in the new material, in the control of the process temperature, the temperature of the extruder, the temperature of the head, and the temperature of the stretching and setting should be appropriately adjusted relative to the new material. The adjustment amount should pass the test. The melt index of the mixture is determined.
On the other hand, since the recycled material is processed a plurality of times, the molecular weight is lowered, a large number of short molecular chains are present, and a plurality of stretching orientations are performed. Therefore, in the production process, the draw ratio is also lower than the same new material. Generally, the draw ratio of the new material is 4--5 times, and after adding 40% of the recycled material, it is usually 3--4 times. Also, due to the increase of the melt index of the recycled material, the viscosity is lowered and the extrusion rate is increased, so the drawing speed of the wire drawing is also slightly accelerated under the same screw rotation speed and temperature conditions. In the compounding of new and old raw materials, it is worth noting that it should be mixed evenly; at the same time, raw materials with similar melt indexes should be selected as much as possible. The melt index differs greatly and the melting temperature differs greatly. In plasticizing extrusion, the two raw materials cannot be plasticized at the same time, which will seriously affect the extrusion drawing speed, resulting in high scrap rate and even impossible production.