The heat shrinkable sleeve is made of high-performance copolymer hot melt adhesive, which is made of radiation crosslinked polyethylene as base material under high-temperature process. Combined with solvent-free epoxy primer, it is suitable for pipeline joint coating and anti-corrosion, forming three-layer structure anti-corrosion coating, effectively protecting steel pipe. And the product in use, also need to have some requirements, heat shrinkable sleeve manufacturers, such as environmental requirements, construction requirements and so on, then we will simply understand it.
Construction environment: air temperature is - 10 - + 50 ℃, steel pipe surface is clean and dry, and there is no welding paste burr on the surface.
Construction tools: liquefied gas tank and spray gun, sand spray (mechanical rust remover), surface thermometer, pressure roller, cotton cloth, etc.
a. According to the requirements of SY / t0407, the oil, grease and other impurities on the anti-corrosion part of the derusting machine shall be cleared.
b. When the weather is wet, the steel pipe should be preheated to 50 ℃ before derusting. The derusting grade is Sa2.5 or st3.0.
c. Trim the external anti-corrosion coating at both ends of the welding joint into a slope, and grind the overlapped parts with abrasive cloth or wire brush.
a. Adjust the baking gun to medium fire to bake and preheat the steel body. The preheating should be even and not too fast, and the temperature around the steel pipe should be consistent.
b. The preheating temperature should be controlled and maintained to 60-80 degrees. Generally, the preheating time should not be less than five minutes, and the time for steel pipes with large diameter is longer.
c. The temperature measurement instrument is used to sample and measure the temperature around the steel body. When measuring the temperature, do not directly measure the bare steel. The measured temperature is to brush a little primer on the bare steel to measure the primer temperature.
a. The primer shall be prepared when the steel body is preheated (the general ratio is a: B = 4:1 or a: B = 5:1).
b. The mixed primer should be uniform, and the primer can be prepared after preheating in winter.
c. Brush with a special brush, to brush 2 to 3 times, so that the thickness is greater than 100 microns.
a. Remove the package from the heat shrinkable tape, and bake the adhesive surface of the heat shrinkable tape with lap wire at a low temperature to make the glue surface bright.
b. The baked end of the heat shrinkable belt shall be overlapped with the steel pipe in parallel, and the lap width shall be uniform, and the heat shrinkable belt shall be firmly attached to the steel pipe.
c. The other end shall be lapped according to the lap joint after the surface of the other end is bright with fire baking glue, and then it shall be sealed at the butt joint with adhesive tape after being compacted with the pressure roller.
d. After baking the adhesive strip with low fire, apply the fixed piece on the upper edge, which should be symmetrical and even. Bake the edge of the adhesive surface of the fixed piece with medium heat and press it on the heat shrinkable belt with a press roller.
e. After the fixing piece is installed, two people (three people are required to operate when the diameter of steel pipe exceeds 1020) start to bake in the middle of the heat shrinkable belt with medium fire (the flame of the two baking guns shall not touch each other and shall be symmetrical), and the baking shall be conducted according to the circumferential direction of the pipe. Slowly bake and shrink from the middle to both sides, not too fast, and move forward after the shrinkage of the heat shrinkable belt is finished (the flame cannot stop at one position, which is easy to bake the substrate).
f. After the completion of shrinkage, the heat shrinkable belt shall be heated with small fire (medium fire for steel pipe with diameter over 457) along the axial direction of steel pipe. When the temperature rises to about 200 degrees (the temperature after removing the spray gun for three seconds) and there is glue overflow on both sides, stop baking.
g. Apply the adhesive tape on both ends of the fixed piece, bake it with low fire, and level it with putty knife. Clean the construction site and finish the operation.
It uses cylindrical film or flat film to wrap the package in a sleeve, and then heat shrinks. After packaging, there is a shrink mouth at both ends of the package.
1. When the cylindrical membrane is used, the opening of the cylinder membrane is opened first, then the product is pushed into the cylinder membrane with the help of the chute, and then the membrane is cut off. The advantages of using cylindrical film packaging are that 1-2 sealing processes are reduced, and the appearance is beautiful. The disadvantage is that it can not meet the requirements of product diversification, and can only be applied to the mass production of single product.
2. There are two ways to wrap articles with flat film: single flat film and double flat film. The film should be wider than the object. Double flat film is used, that is, the upper and lower films are wrapped. When the previous package is sealed and cut, the two films are sealed. Then the product is pushed to the vertical film by machine or hand. After the sealing and shearing mechanism is in place, the other side of the product is sealed and cut. After the product wrapped with film is heat shrinked, both ends of the package are closed When a single flat film is used, the flat film is first unfolded, and the wrapped product is sent to the middle of the flat film to form a horseshoe shaped package, which is then reheated and overlapped.
The process of plasma surface treatment with heat shrinkable sleeve is to produce low-temperature plasma when glow discharge or high-frequency discharge. First, the electron becomes high-energy electron under the action of electric field. If its energy is greater than the excitation energy of gas atom or molecule, the gas atom or molecule colliding with it can produce excitation molecule, excited atom, ion and radiation line.
These high-energy particles or radiation lines can cause physical and chemical changes on the surface of the heat shrinkable sleeve. Low temperature plasma can be divided into reactive and non reactive. The more commonly used reactive plasma is oxygen and nitrogen plasma, which not only changes the structure of polymer, but also changes the chemical composition of polymer surface because of its high chemical properties.
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