Brief description of recycled polypropylene plastic process technology

The raw materials of plastic woven products are mainly polypropylene and high-density polyethylene. The auxiliary materials generally include modifiers, lubricants, masterbatch and so on. According to the different uses of plastic woven products, the choice of raw materials is also different.

In general, high-density polyethylene braided cloth has good hand feeling, softness, and low temperature resistance. Polypropylene, on the other hand, has a rich source and low price, so polypropylene is widely used as the main raw material for plastic woven products.

The molding of plastic products is extrusion molding. In order to ensure the quality of flat-type chaos-shaped workpieces, it is generally preferred to select the proper raw material for the melt flow rate (MFR). Polypropylene melt flow rates commonly used in plastic wovens range from 2 to 5 g/10 min. The melt index is small, and the strength of the flat yarn is high, but the molding is difficult. On the contrary, the flat yarn has low strength and molding is easy. If a large amount of filler modifier is added to the formulation, the flowability of the material during the molding process will be reduced, and a small amount of plasticizer or lubricant may be added to improve the fluidity.

At present, polypropylene recycled materials are also used in the production of plastic woven products. Although their physical properties and quality are worse than new ones, they can also meet the required standards as long as they are reasonably selected. If the flat yarn produced from recycled materials is not shiny, a small amount of lubricant can be added to the raw material formulation to improve.

For the selection of polypropylene recycled materials, "a look at two bites three fired four pull" to see the appearance of renewable materials, the surface was waxy, dark and no bubble is a better renewable material; gather particles on the teeth On the bite, the harder is the polypropylene renewable material particles, the bite is a better PP renewable material particles, the softer is the PE type renewable material particles; the particles on the flame to ignite, can leave the flame to burn on their own The color of the flame is blue at the bottom and yellow at the top, and there is a lot of black smoke and molten dripping during the burning process. The regenerated PP material emits petroleum odor; the PP regenerated material that can continuously pull the filaments in the molten state, Pull out the short silk head and burn particles of polyethylene regenerated material that resemble wax odor.

The main equipment for producing plastic flat yarn is an extrusion molding machine. The raw material after drying is 180-250°C, and the molding temperature of the recycled material is controlled at 150-200°C. The molten material should be filtered when it passes through the tee under pressure.

There are three main purposes of filtration: one is to filter the impurities in the material; the second is to stabilize the flow of the material; the third is to make the product compact. Most of the filters currently used are 60 mesh high-elastic steel screens. In general, the number of layers of the filter should be 15-30 layers (depending on experience), too little flow instability, the product is not dense; too much resistance is too large and burst three links.

The filtered molten material should be cooled immediately after passing through the die. The cooling method is usually water-cooled. Cooling temperature should be controlled at 30 ~ 35 °C is appropriate. Cooling the material has three purposes: one is to set the melt; the other is to avoid high-temperature oxidation; and third is to prevent the crystallization of the material, providing the necessary conditions for hot stretching.

After the extruded melt film is cooled, a suitable knife pitch is selected according to the type of the flat yarn. When cutting, try to keep the cutting uniformity of the flat film. After cutting, the flat film is subjected to a heat stretching process to obtain a flat yarn with a large pulling force, but in order to prevent the flat yarn from undergoing a large shrinkage during the subsequent weaving process, heat setting treatment should also be performed on the flat yarn.

Flat film in the hot stretching and heat setting treatment according to the different materials and flat wire to select the appropriate temperature and traction ratio. Generally, the hot stretching and heat setting temperatures of the new material are about 120° C. and 100° C., respectively, and the traction ratio is about 1:5.8; the hot stretching and heat setting temperature of the recycled material are about 100° C. and 90° C., respectively. Around 1:5.

In addition, the type of flat yarn and gram-weight ratio are different, and the heat stretching, heat-setting temperature and traction ratio are also not the same. The relatively large gram-weighted flat yarn may also have a slightly larger temperature and traction ratio; otherwise, the temperature and The traction ratio is slightly smaller (according to the usual experience and mechanical properties).

The flat film can be used for the knitting of a circular loom after hot stretching and heat setting treatment. At present, most circular looms of the woven factory are four-spool circular looms, and their rotation speed is generally 100 to 130 rpm. The four-shuttle circular looms are relatively stable and can be used to weave a wide variety of widths. Tubular cloth bag surface smooth, smooth, with high quality.

The woven bag made by cutting, printing and sewing the woven tube cloth can be used for packing various types of materials in various industries.

Regeneration PP polypropylene process

Most of the PP come from daily necessities, plastic boxes, basins, buckets, rice scouring, plastic chairs, stools, weaving bags and other packaging woven fabrics, packing belts and so on.

1. First, separate the colors of various materials, because the separation will make the user convenient and the price can be high.

2. With water crushing and rinsing, drain the excess water to the dryer, then dry it and bag it. Mix with a mixer and add color and additives.

3 special plastic machine for granulation on the train, but the granulation temperature can not be too high, easy to brittle, so be sure to pay attention to temperature.

4. Water-cooling pellets, to standard 3X4mm, otherwise the appearance of even the best material does not look good, not standard.