Easy to see problems in the production process of

2022-09-21
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The production process of liquid milk packaging film is easy to see problems

in 2003, the market scale of plastic flexible packaging film for ultra-high temperature sterilized milk alone was about 50000 tons. From the perspective of geographical distribution, it is mainly the dairy companies in the north and Jiangsu and Zhejiang that adopt this form of packaging. Now, the structure of milk film is developing towards high barrier and environmental protection. With the development of the dairy market, the demand for milk film is increasing rapidly, with an increase of more than 20% in 2004. Therefore, many plastic packaging companies have entered the milk film market, making the market competition increasingly fierce. In addition, it is an indisputable fact that the price of plastic raw materials continues to be high this year, and the profit is reduced. Therefore, in the near future, plastic packaging companies must carefully investigate and carefully position before entering this market, so as to avoid investment mistakes

the problem facing the milk film production enterprises now is to develop new barrier materials to reduce costs, otherwise there will be fierce competition across the country, and as a result, some enterprises will face the situation of shutdown and semi shutdown In particular, some enterprises recruit some so-called experts and talents Some people have reduced the thickness of EVOH film to about 5 microns. In fact, the performance requirements of most multi-layer coextrusion equipment are not allowed. As a result, the film thickness is uneven, which seriously affects the printing, causing the filling deviation of dairy production line, etc., and brings waste of materials to the enterprises using milk film The heat sealing layer of some 7-layer equipment is twin-screw, and the extrusion volume is required to be large, while some able-bodied people simply don't understand why to use twin-screw, copy the proportion of 5-layer equipment to determine the extrusion volume of the outer layer, resulting in the destruction of the balance relationship of the 7-layer structure and damage to the equipment. Some screws start to wear fast, need to be replaced in a few months, and some don't reduce production

people in the industry know that excellent heat sealing performance can ensure that fresh milk has a wide heat sealing temperature range on the automatic packaging line, which is conducive to improving the packaging speed, and the seal will not break the bag during refrigeration and transportation. Therefore, Metallocene Linear low density polyethylene (mLLDPE) with high and uniform branching degree and narrow relative molecular weight distribution is used in the heat sealing layer to improve the heat sealing performance of the film. MLLDPE heat sealing temperature range is wide (100-1 to meet different needs 35). Ordinary LLDPE is (115-135 degrees), and the heat sealing strength of mLLDPE is significantly higher than that of ordinary LLDPE. Although mLLDPE structure has a large degree of branching, due to the short branching chain, its melt strength is low and its processability is not good, so a certain amount of LDPE needs to be added to improve the stability of the membrane bubble and improve the processability

fresh milk is packaged in the following ways: vertical molding filling heat sealing (VFFS) automatic packaging. When the black-and-white film is loaded, the heat seal is cut off and the next bag of milk begins to fill. If the heat bonding strength is not high, the bag will be directly broken under the impact of fresh milk. For this reason, mLLDPE (density = 0.919) with relatively high molecular weight and dense maxtest software supporting windows 98/x will be selected, otherwise the test results will be inaccurate. The low degree of p/2000 and other windows operating systems will ensure the high thermal bonding performance of the film. Compared with ordinary LLDPE (density = 0.925), the thermal bonding strength curve of mLLDPE film moves to the low heat sealing temperature zone, and the thermal bonding strength is significantly higher than that of ordinary LLDPE, which meets the rapid packaging requirements of automatic filling machines

in this way, some metallocene 1018fa is required for the heat sealing layer used for milk film, and this material is not used for the inner layer at all. But now it is found that there are individual 7-layer milk film manufacturers in China, which also use 1018fa for the adjacent layer of the heat sealing layer, and the proportion reaches 60% of this layer, which is an obvious waste of metallocene raw materials. One is that he doesn't understand it, and the other is that if he understands the reason, he is suspected of reselling raw materials with raw material suppliers. Some charlatans are holding an annual salary of 100000 yuan while secretly colluding with raw material suppliers to use more valuable raw materials, from which they charge good. The pendulum type film impact tester of Jinan new era Gold Testing Instrument Co., Ltd. is mainly applicable to the determination of plastic The impact toughness of film materials such as rubber and metal foil is the problem faced by some enterprises in the production process at present

reprinted from: China Business Forum

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