Biaxially oriented film for composite coating production line
DATE：2021/4/22 8:48:06 / READ： / SOURCE：This station
Biaxially oriented film for composite coating production line
Composite coating production line www.handern.comBiaxially oriented (oriented) thin films are formed by extrusion blow molding and extrusion tape casting. After the films are quenched to quotient elastic state, they are stretched longitudinally and transversely in high elastic state. The tensile results not only make the films thinner in macroscopic view, but also make the polymer molecules arrange orderly in stress direction in microscopic view. The orientation of polymer molecules greatly improves the physical and mechanical properties of polymers. Thinner films or products with smaller wall thickness can be used to obtain many times higher mechanical strength. On the basis of saving polymer materials, high packaging performance can be obtained to meet the packaging requirements. Therefore, although it was only developed in the 1970s, it has developed rapidly. It is the most important packaging material in flexible plastic packaging and hollow container packaging. It must be pointed out that biaxially oriented films all lose heat sealing property, and although the induced tear strength is slightly increased, the secondary tear strength is greatly reduced, and the whole film is torn with a little force. For this reason, the biaxial directional film slitting knife should be very sharp, the incision should be neat and smooth, and there should be no cutting marks, otherwise, it can not be printed on the printing machine or compounded on the laminating machine, and it is easy to be torn and cracked by the tension. The BOPP film produced with heat sealable BOPP special material has a certain heat sealability, which is generally a blend or copolymer containing rubber or low melting point particles. Composite coating production line www.handern.com
There are three ways to produce biaxially oriented films.
1、 Blowing method and biaxial drawing method
Firstly, the investment of equipment is less than 1 / 10 ~ 1 / 15 of that of flat film process; Second, the operation is relatively simple, the floor area is small, and the workshop is not large; third, the drawing ratio is relatively small. Only the process of b0p front film produced by the phase bubble method of the engineering company is used to explain the parameters of the equipment: screw straight light b5m, Downblow water quenching method, main motor power 22kw, adjustable speed, round die head, die lip diameter 70mm. The heating power of the extruder is 16kw, 4 sections, die head: 1 section, 1kW heating power and 6kW die lip heater. The water temperature for quench is 5 ~ 10C. The equipment is produced by Japanese engineering company. Composite coating production line www.handern.com
technological process:
PP raw material → extruding thick film in extruder, water quench > heating in heating tube to a high elastic biaxial stretching temperature of TG ~ t → firstly, the longitudinal traction roller rapidly pulls 5 ~ 7 times, then, the transverse expansion is 5 ~ 7 times, cooling and winding, unwinding on the setting equipment, heating step by step to the setting temperature, holding for a certain time under the setting temperature roller cylinder → cooling roller gradually cooling → corona treatment ”Take up the finished product. Composite coating production line www.handern.com
BOPP blowing method operating parameters: thick film extrusion temperature: barrel temperature: when using f-5361 (MFR 1g / 10min, OPP special brand): 220c, 230C, 240C, 240C, connector 240C, die lip temperature (die): 230C, when using xf-2376 (MFR 2.5g / 10min, OPP special brand) produced by nippono company, Heat sealable OPP film special material grade: 200C, 210C, 220c, 220'c, connector: 220c, die 220'c. The thickness error of thick film tube should be controlled below 2%, and the quench water temperature should be 5 ~ 10C. Because PP is a typical crystalline polymer, it is necessary to use quench method to make PP amorphous before crystallization, and then heat it to high elastic state for biaxial stretching. Quench is very necessary for crystalline polymer, but for amorphous polymer, such as PVC, It can be directly cooled to the drawing temperature for biaxial drawing, but the amorphous polymer can't heat set the oriented molecules, which will shrink when heated, and can produce heat shrinkable films. Composite coating production line www.handern.com
The drawing box is a tube shape with three heating sections of 2.5m in length. The first preheating section is 24kw, and the second preheating section is 18kw. The heater is used to heat the air, and the hot air is blown into the thick film to heat the thick film. The heater is installed in front of the pinch roll. The two preheating sections and one drawing section are respectively equipped with three pairs of pinch rolls (composed of a steel roll and a rubber roll). The heating power of the drawing section is 5.5kW.
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