Precautions for manufacturing the hottest breathab

2022-08-21
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Precautions for the manufacture of breathable films

films are used more and more widely. Among them, breathable films have been vigorously developed, and their applications can be seen in food, medicine and sanitary products. The production of breathable film involves all parts of the production line, and every procedure also has something to pay attention to

a set of tensile loading time assays. This machine is widely used in tensile, compression, bending, shear and other mechanical property experiments of metal and non-metallic materials; By configuring a wide variety of accessories, Japan took the lead in developing breathable films for the health industry as early as 1983. The production of breathable films began in the United States in mid-1990. This product entered Europe in about 1995, and since then, its market share has increased year by year. The normal procedure for producing breathable films is to first prepare the base materials, PE or PP base materials respectively, and add 40% - 60% calcium carbonate to the mixture or masterbatch. Then stretch on the flat extruded film or blown film line. After stretching, the calcium carbonate crystal partially separates from the polymer matrix. In this way, microchannels are formed in the film section, so that water vapor can pass through in the later stage

material drying/feeding

in order to ensure that the humidity of raw materials used in the production of breathable films is controlled to a minimum, the materials should be pre dried by a dry air drying device before processing. If the residual humidity is too high, non stretched and stretched films will form pores. The materials are loaded into the drying hopper and extruder through the vacuum adsorption conveyor, and then the dust-proof weighing device is used to feed each component

extrusion

in terms of product quality, the requirements of breathable film extrusion are extremely high. The high-performance single screw extruder used is equipped with a long processing device with a diameter of mm. In principle, the screw diameter is between 75 and 150 mm. The former is applicable to the co extruder and the latter is applicable to the main extruder. Liquid piston filter and screen belt filter are used for melt filtration

feeding head/die head

breathable film is mostly composed of three layers, sometimes only one layer. If a three-layer structure is adopted, the outer layer should be made of 100% raw materials, and the middle layer can be recycled. The quenching and extraction device first casts the melt base material on a matte steel roller with a diameter of 800 mm. The next quench roll is a high gloss roll with a diameter of 400mm. The basic mold base includes solid side walls, and the first measuring mold base is directly assembled on the quenching device

thickness measuring device and base material inspection

two groups of thickness measuring devices can be installed on the cast film line with stretching device. Among them, the first group of measuring devices is used to measure the original film, and the second group is used to measure the film after passing through the stretching device. The plane thickness specification is set in the second measuring device. The system develops target specifications for the first measuring device, which also takes into account the original data of the film when stretching. This information is further transmitted to the die. The intelligent linear digital camera scans the film substrate to check whether there are pores to ensure quality. The recorded data is classified according to the system definition, width, length and target position

stretching device

the film that has not been stretched enters the stretching device. Here, the film is raised to the stretching temperature by the preheating roll, and then uniaxial stretching is carried out between the stretching roll gaps. After stretching, the molecular structure is frozen on the stabilizer roll, so that the material can no longer return to its original shape. The breathable film used in the health industry is usually embossed after stretching to reduce the gloss of the film from fluorite primary processing to the industrial chain of functional film materials, so that the film has the feel of textiles using the structural characteristics of the machine

unwinder

the full-automatic nonwoven unwinder has the same principle as the indexing winder and is installed above the laminating device

laminating device

using hot melt laminating device, non-woven fabric can be pressed on breathable film. The hot melt is continuously coated on the nonwoven fabric, and then pressed together with the film. Most of the hot melts used for lamination are rubber based viscose

edge cutting/recycling

film edges and corners are cut before entering the stretching device, laminating line and winder. If it is necessary to have circulating air in the corner test box, the material is pure film, which can be sent back to the process for reuse. This recycling process is usually completed by horizontal waste extruder or recycling system

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