Selection of commonly used woven bag materials
DATE：2022/5/28 8:40:04 / READ： / SOURCE：This station
Selection of commonly used woven bag materials
The raw materials for woven bag production are mainly polypropylene and high-density polyethylene. According to the source of raw materials, market needs and price conditions, each has its own emphasis on selection. In China, 200 woven bags of high-density polyethylene are the main raw materials. After the 1970s, with the development of domestic industry, polypropylene raw materials are rich in sources and low in price, so the woven bag production has turned to polypropylene; However, the flat filament produced with high-density polyethylene has good post-processing performance, soft handle, weather resistance and low temperature resistance, which is better than the fabric produced with polypropylene. Casting film production line www.handern COMIn addition to the market supply and demand, the raw materials for the production of flat silk are mainly considered from the technical aspect, such as extrusion processing characteristics, application characteristics and mechanical properties. The raw materials required for the production of woven bags belong to the category of extrusion grade resins. After the resin is determined to be extrusion grade, the focus is to select the molecular weight of the resin, that is, to select the melt flow rate of the resin. If the required strength of flat filament is high, the melt flow rate should be lower; On the contrary, higher melt flow rate can be selected to facilitate molding processing. Generally, the melt flow rate of high-density polyethylene is 0.5~1.2g/10min, and that of polypropylene is 1.5~5.0g/10min. The higher the melt flow rate of polypropylene, the better the fluidity. Adding filler such as master batch to polypropylene will reduce the fluidity of the resin. Adding plasticizer and lubricant can improve the fluidity. Casting film production line www.handern COM
Polypropylene can be mixed with polyethylene. Adding less than 15% polyethylene to polypropylene resin will not affect the quality of flat filament, but also increase the brightness of flat filament. New polypropylene material and recycled polypropylene material can be mixed at any ratio. In addition to polypropylene particles or powders, when purchasing recycled material particles, you should "look at them, bite them, and pull them.". Look at the appearance of recycled material particles; Class a recycled materials are white, bright and translucent in appearance, class B recycled materials particles are black, bright and bubble free in appearance, followed by class C recycled materials particles. Take several recycled material particles and bite them on the teeth. It is obvious that they are polypropylene recycled material particles. The particles that bite constantly are better, and the ones that bite soft on the teeth are polyethylene recycled material particles. Take a few particles to ignite and melt, which can continuously pull out 16 wires. The particles with petroleum smell are polypropylene recycled materials, and the particles with wax like combustion smell are polyethylene recycled materials. The application of recycled materials should be selected according to the different uses of the products. Of course, after the recycled materials are used, the physical properties and quality of the products cannot be compared with the new materials. However, as long as they are properly used, they can also meet the quality requirements.
At present, polypropylene based woven bags, in addition to transparent bags, more or less should be properly filled with masterbatch. Pay attention to the thickness when selecting master batch; The filler masterbatch with high activity, reinforcement and processing performance shall be prepared from light calcium carbonate and active calcium carbonate. The filler masterbatch shall be added according to the brightness, whiteness and tensile strength of the woven bag, generally accounting for less than 25% of the total content. Casting film production line www.handern COM
If the surface of recycled particles is not glossy and dry, adding 1%~1.5% paraffin can increase the lubricity and brightness of flat wires.
In order to meet the needs of application, 0.3%~0.8% coloring pigment is generally added to the colored woven bag products. When selecting, the coloring pigments are generally required to have the following characteristics: good light resistance and heat resistance, good dispersion and coloring power, good electrical insulation, acid and alkali resistance, and moderate price. For the colors of woven fabrics that need to be prepared, some coloring pigments are not available in the market, and several coloring pigments need to be selected for color matching to meet the required colors. In color matching, woven bags with low requirements and recycled materials can be filled with masterbatch instead of titanium dioxide, and other coloring pigments can be adjusted appropriately. If most or all of the woven bags are produced from recycled materials, the pigments of titanium dioxide and masterbatch (because the recycled materials contain titanium dioxide and masterbatch) and carbon black can be removed, or other coloring pigment components can be added. Production procedure of plastic flat wire: add the dried plastic raw material into the hopper, and the raw material enters the screw groove of the material barrel. The raw material is forcibly pushed to the machine head from the thread direction by the continuous rotation of the screw.
When the plastic is extruded, the film with viscous flow state immediately enters the cooling water tank for rapid cooling to form a film. The longitudinal strength of the flat wire is increased by cutting and then passing through the hot plate at the back of two groups of ovens, and then coiling. After heat treatment, the elongated molecules of the flat wire are oriented under the action of tensile force. Casting film production line www.handern COM
1、 Preparation before startup (1) materials, such as agent, recycled material particles, filling masterbatch, coloring pigment, filter screen, double-sided blade, etc. Receive special tools and other operating tools. (2) check whether the thermometer is normal. If any abnormal phenomenon is found, repair it immediately. If everything is normal, first heat the temperature of tee and die head (because the temperature of tee and die head rises slowly). When the temperature of the tee die head reaches a certain value (based on the data obtained from ordinary experience), start the heater, and finally start the heaters of the two ovens. (3) The system shall be adjusted to the required temperature, as shown in table 1-5 and table 1-6. The extruder temperature shall be changed according to the sensor position, plastic characteristics and recycled material proportion. The temperature of the oven depends on the position of the sensor and the draft ratio. In short, the draft ratio increases when it is high and decreases when it is low.
Author：admin