Plastic film extrusion

日期:2022/9/22 8:48:01 / 阅读: / 来源:本站

                                                                                                                                                  Plastic film extrusion
Plastic film extrusion molding refers to plasticizing and melting in the machine with polymer synthetic materials as the main trimming material, and then extruding from the molding die, and after blowing or flowing, it becomes a certain thickness (thickness is 0.01~ 0.25mm) limited length, flat surface, smooth and soft plastic products.
(1) The polymer synthetic materials used to form plastic films are resins such as olefin, polypropylene, polyvinyl chloride, polyester, polystyrene, polyvinylidene chloride, polyvinylidene fluoride, polycarbonate and polyurethane. Among them, polyethylene and polyvinyl chloride resins are the most widely used, and the film products produced by these three raw materials are the most widely used.
It accounts for more than 4/5 of the total output of plastic film.
(2) There are no uniform regulations for the classification of varieties of plastic films. usually people
There are three types of classification.
①The raw materials for plastic film forming are classified into polyethylene film polypropylene film
PVC film and polyester film, etc.
② According to the use of plastic film, agricultural film can be divided into plastic film and greenhouse film according to the use of agricultural film; packaging film (packaging film can be divided into food packaging film and packaging film for various industrial products according to its specific use. etc.) and breathable films for special environments and special purposes, water-soluble films and films with piezoelectric properties, etc.
③ According to the molding method of plastic film, there are extrusion plasticized and then blow-molded films, which are called blown films; after extrusion and plasticization, and then the melted materials are cast from the die mouth. Films are called cast films. ; A film made of plasticized raw materials rolled by several rollers on a calender is called a calendered film.
(3) The application of plastic film can be seen everywhere: used for mulch film, greenhouse film and packaging of various agricultural products in agricultural production; used for various industrial production in industrial production
Packaging of Chinese clothing and food, protective equipment, and decorative pins for toy machines. Composite film for military surface (wood, steel, paper, etc.) and packaging with Wuzhu Electric Power Division (mechanical parts, instruments and meters, household appliances), air film, water-soluble film, insulating film, piezoelectric sea-level Machine radiation protection equipment, etc., ground plastic film in the development of the national economy and people's daily life
often extensive. this.
(4) Features of extruder forming film
The project investment is small, the production time is short, and the economic benefit is good. ①Extruder forming plastic film production equipment occupies a small area, and the equipment structure is relatively high
one,
② The extrusion method is used to form the film. When blow molding is used, the product is round and simple, and its circularity
Pen size is easier to control.
③The operation of the equipment for forming the film by the method is relatively simple, and the production technology of plastic film is relatively simple.
School to master.
⑤ The width of film products can reach more than 10m. ④Thin products are cylindrical, the finished products do not need to be trimmed, and waste is rarely generated.
@The working strength of the plastic film formed by extrusion blow molding is lower than that of the thin film produced by the calendering method, the thickness deviation is also relatively large, and the product quality is not stable enough.
According to the production method of plastic film extrusion molding, in the plastic film extrusion molding production line, the extruder is the main machine, and the auxiliary machines also have corresponding layout types. Figure 6-1 shows the arrangement of auxiliary machines on the extrusion blow molding film production line. Figure 6-2 shows the arrangement of auxiliary machines on the extrusion cast film production line. Figure 6-3 shows the arrangement of auxiliary machines on the extrusion and traction film production line. In addition, there is an extrusion stretch film production line. The molding of this film is firstly produced by an extruder to form a flat sheet (as shown in Figure 6-3), and then the film is formed by longitudinal and transverse stretching.
6.1.1 Auxiliary Machines in Extrusion Blown Film Production Line
There are three types of auxiliary machine arrangements on the extrusion blown film production line, as shown in Figure 6-1. Figure 6-1(a) is the up-blowing method, which is mostly used for polyvinyl chloride, polyethylene and polypropylene resins
1-Extruder, 2-Forming die; 3-Three-roll calender: Taiwan printing flow selection type, Figure 6-3 Extrusion and traction forming film (sheet) equipment arrangement 5-Edge trimming device, 6-Drawing device: 7-cutting device: 8-finished product inspection or winding device
Extrusion blown film production. This production line has a small footprint, easy operation, stable operation of the ground pipe, and can produce large-diameter films. Figure 6-1(b) shows the down blow method, which is mostly used for extrusion blow molding of polypropylene, polyamide and polyvinylidene chloride (PVDC) resins. Large resin production, convenient cooling and cooling of the film, and extruded film at a higher production speed. Figure 6-1(c) can be used for polyethylene, polyvinyl chloride and polystyrene resin extrusion molding. The folding diameter is flat blowing method, and the film production is not larger than 300mm. The structure is simple and the operation is more convenient. As can be seen from Figure 6-1, the equipment for blown film extrusion molding includes: extruder, forming die, cooling air ring, herringbone guide plate, traction device and coiling device. The selection of the host used in plastic film extrusion blow molding has been introduced in Chapter 3. Generally, the extruder used for forming film by extrusion blow molding method is mostly single-screw general-purpose extruder; The depth is gradually shallower), the aspect ratio is greater than 20:1, and the compression ratio is 3~4. The diameter of the screw can be selected according to the width and thickness of the film product and the data conditions in Table 6-1.

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