The hottest laminating bag and coating bag

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At present, plastic woven bags used for the packaging of food, cement, salt, fertilizer and other substances are generally required to have high moisture-proof, dust-proof, leak proof and other properties, while ordinary woven bags are difficult to have these functions at the same time. In order to make the woven bag meet the above requirements, there are still many ways to explore the woven bag by yourself: one is to set a lining bag in the woven bag; The other is to press or fuse a layer of film on the surface of the woven bag to achieve the purpose of moisture-proof, dust-proof and leak proof. For the first method, because of its high cost, cumbersome operation and low efficiency, most of them now use the second method

previously, we referred to woven bags with a layer of film on the surface as laminated bags. However, according to the different laminating methods, they are now divided into laminating bags and coating bags. Generally speaking: under the pressure of heating roller and rubber roller, the woven bag made by pressing the film on the woven cylinder cloth is called laminating bag; The traditional tape casting technology is used: the molten material is coated on the woven cloth, and the woven bag made of the molten material is cooled and compounded on the woven cloth under the pressure of the cooling steel roller is called the film bag. Both film coated bags and film coated bags are woven bags made by laminating a layer of film on the woven cloth. However, due to their differences in production equipment and molding process, their product quality and performance are very different

the production equipment of coating bag is the coating machine, which is actually the extrusion molding machine of double die. The forming process of the coating bag is as follows: first, the coating machine melts and plasticizes the raw materials, and then extrudes and coats them on the woven fabric substrate through a double die; Then, under the action of two cooling steel rollers (water cooling), the melt film is cooled to form a composite film on the surface of the woven fabric. The woven bag made in this way is called film bag. The coating machine is fast and efficient in the production process. The surface of the coating bag produced is flat and smooth, with high surface quality. The film bag has good moisture-proof, dust-proof, leak proof and other properties, and can basically meet the specified use requirements. However, because the coating machine directly coated the woven cloth with molten materials with higher temperature (above 200 ℃), it is easy to cause the woven cloth to overheat and affect the physical performance indicators of the coating bag

generally, there are three choices of coating materials: one is high-density polyethylene (coating grade); One is the combination of low density polyethylene (coating grade) and special PP coating material; The other is the combination of high-density polyethylene and low-density polyethylene (coating grade). These three options have their own advantages and disadvantages and scope of use. At present, most manufacturers use the second option: the combination of low-density polyethylene (coating grade) and special PP coating material. However, due to the different manufacturers, the proportion of raw materials is also different. Generally speaking, the ratio of low-density polyethylene to special PP coating material should be about 3:7. In addition, according to the requirements of product performance, the proportion can also be 4 to 6 or 2 to 8. However, the increase of PP coating material in the proportion will make the texture of the coating bag more brittle and hard

the production equipment of laminating bag is laminating machine. The forming process is as follows: the film blown with a special formula is compounded on the woven fabric substrate, and the film and the substrate are pressed together under the action of the heating roller and the rubber roller (about 100 ℃), forming a layer of composite film on the surface of the woven fabric. The woven bags made in this way are called laminating bags. The surface of the laminated bag is flat and bright, and its moisture-proof, dust-proof, leak proof and other properties are also high. Because the laminating bag presses the film on the braid, which improves the resultant force between the flat wires of the cylinder cloth, the tensile strength of the laminating bag is high. Compared with the coated bag, the hard wrapping rate of the coated bag is much smaller. 3. Different fixtures are designed according to different samples and experimental methods. However, because the laminating bag is heated for a long time in the forming process, the woven tube cloth shrinks, which affects the accuracy of the width of the laminating bag. In general, the width of woven tube cloth with a width of 50cm will shrink by about 2cm after laminating

due to the different production equipment and molding process between the laminating bag and the coating bag, its appearance is also different:

1. The surface of the laminating bag is flat and shiny, while the surface gloss of the coating bag is poor

2. The texture of the film coated bag is soft. The oil pump motor must not be started, and the folding resistance is good, while the texture of the film coated bag is hard, and there are creases after twists and turns

3. The surface of the laminated bag is seamless and boundless, while the coated bag generally has burrs. In addition, the current composite film bag and coated strand bag are made of a layer of film on the outer surface of the woven tube cloth. In the process of use, the outer film is easy to be damaged, and cannot have the functions of moisture-proof, dust-proof, leak proof and so on. This is a common disadvantage of film coated bags and film coated bags

from the above analysis, it can be seen that the quality of the laminated bag is higher than that of the coated bag. However, the production cost of laminated bags is higher than that of coated bags, and the production efficiency is lower than that of coated bags. Each manufacturer can selectively produce coated bags or laminated bags according to their actual situation and customer requirements

2) declare according to the shape of the sample clamping end:

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