Crosslinked film manufacturer - heat shrinkable packaging -2
According to the different manufacturing methods and use range, the shrinkable thin film is roughly divided into: one is the two axis extended heat shrinkable film (the crosslinking film belongs to this type), and the two axial extension of the film is almost equal during the process of processing; the other is an axial extension heat shrinkable film. When the film is made, it extends only in one direction. The two axis film has a wide range of applications, which can be used for packing fresh food or pallet packing, and one axis film is commonly used in tubular shrink packaging and label packaging, such as label packaging for wine containers, label packaging of mineral water, beverage bottles, sealed packaging of plastic bottles and glass bottle covers, and fresh fruit and vegetable cannula. Packing and so on.
The main performance indexes of the shrinkable film
1. the shrinkage ratio and shrinkage ratio include both longitudinal and transverse. The test method is first to measure the length of the film L1, then the film is immersed in 1 ~ 3s of glycerol at 120 C, and then cooled by cold water after taking out and then measuring the length of Ll in the length L2 type for the length of the thin film before contraction; L2 is the length of the thin film after the contraction. At present, the shrinkage film used in packaging generally requires equal shrinkage in two directions, about 50%, but in special cases, there is a one-way contraction and the shrinkage rate is about 25% to 50%. There are also vertically stretched thin films with two opposite directions. The ratio of contraction rate in two directions is called contraction ratio.
2. contraction tension contraction tension refers to the tension exerted on the packaging after film contraction. The shrinkage tension at shrinkage temperature is closely related to the product's protection. Rigid products such as metal cans can be used to allow larger shrinkage tension, while some fragile or easily wrinkled products will be deformed and even damaged due to excessive shrinkage. Therefore, the shrinkage tension of the shrink film must be chosen properly.
3. shrinkage temperature shrinkage film starts to contract after reaching a certain temperature after heating, and the temperature rises to a certain height to stop shrinkage. The temperature in this range is called the contraction temperature. For packaging operation, the temperature of the packaging is heated in the heat shrinkable channel, and the temperature reached when the film shrinkage produces a predetermined tension is called the shrinkage temperature under the tension. There is a certain relationship between shrinkage temperature and shrinkage rate. In shrink packaging, the lower the shrinkage temperature, the smaller the adverse impact on the packaged products, especially fresh vegetables, fruits and textiles.
4. in the heat shrinkable shrink packaging operation, before heating and contracting, it is necessary to have two or three sides thermal sealing first, and the sealing strength is higher. The commonly used sealing methods in packaging are thermal sealing, pulse melting sealing, radiating sealing and ultrasonic sealing. Heat sealing is the most common method. When the seal is closed, the plate (or disc) heated to a certain temperature is pressed onto the overlapping film to seal. In order to prevent the film from contracting heat, it should be fast sealed. It is better to take timely cooling measures immediately after sealing. After pressing the film with nickel chromium alloy wire, the impulsive fusing sealing method makes the nickel chromium alloy wire heating through a large current, so that the film is heated and fused and then released after cooling. The radiation sealing method is a nickel chromium alloy wire or a metal sheet with a sharp mouth, which is used as a heating body, embedded in the V groove of insulating an insulating heat body made of ceramics and other materials. When the film is heated, the film is fused by the radiation heat of the alloy wire. Ultrasonic sealing method is to use an oscillator to produce ultrasonic wave, make one vibrator accept and convert into longitudinal vibration, rely on conical honing head, propagate vibration, make the two thin film recoincide with friction heat and melt, it is suitable for continuous sealing of heat shrinkable film automatic packing machine, and can also be used for film impregnated by water, oil and sugar. Good bonding.
Crosslinked POF has high shrinkage, strong contraction tension, wide contraction temperature range, and super thermal sealing. It is the first choice in heat shrinkable packaging.
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