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Overview of Extruded Cast Film line
Compared with the extrusion blown film, the film produced by the extrusion casting method has the advantages of good film transparency and good thickness uniformity. Cast film resins are mainly polypropylene, polyethylene, polyamide, etc.
In order to manufacture extruded cast film, on the extruder, the opening shape of the die of the die through which the plastic melt flows is a slit, called a slit die, and the melt forms a continuous rectangular cross-section through the slit. Body, the width of its cross-section is much greater than its thickness. The extruder casts the molten film down to the surface of the cooling roll through the die. After cooling and shaping, it is drawn, trimmed and wound to make a single-layer cast film. The film thickness is 0.05~0.1mm.Films and sheets are made by squeezing the melt onto quenched chrome-plated rolls. The melt leaving from the slit is cast down or at a certain angle onto the cooling roll, touching the roll in the tangential direction, the surface of the roll is very smooth, so that the surface roughness of the film is also very low. Generally, before the film is cooled to be cut and wound, the film must pass through a set of S-shaped rolls and at least two quench rolls. The working temperature of the first cooling roll is at least 40¡ãC. The air blowing nozzle is used for cooling. The film produced by this method has better transparency and higher toughness, and the production volume is high. The size of the film mainly depends on the extrusion rate and the pulling speed.
In this processing method, due to the cooling shrinkage of the film, the size of the film or sheet made is smaller than the size of the die, and the edge part will become thicker, and the thicker part must be cut off. Similarly, when the film is rolled, due to the unevenness of the thin thickness, the thickness variation is further increased, resulting in violent ribs. The normal deviation of the film thickness is ¡À3%. The violent ribs generated in the film will cause difficulties in subsequent operations. , There are two ways to reduce the ribs. The general traditional method is to swing the film during the winding process to produce random thickness changes. The biggest disadvantage of this method is to reduce the width of the film and increase the amount of waste, but These waste materials can be reused as recycled materials. A more advanced method uses sensors to detect the thickness of the film in real time, and automatically adjust the required die gap through computer control.
The film can be "oriented" or stretch the film under certain conditions, so that some molecules are rearranged in the stretching direction. This arrangement will remain after the external force is removed. The orientation can increase the crystallinity, improve the barrier properties, and strengthen the stretching direction. The strength weakens the strength in the unstretched direction.
Company Profile
Nanjing Sumino Precision Machinery Co., Ltd. is a high-tech enterprise integrating scientific research, production and sales. It has always adhered to the business philosophy of integrity, equality, and customer benefits. In order to better improve the quality of equipment, it has entered a more professional and standardized Production track. We have established independent research and development technologies for seven categories of equipment including plastic sheet material, casting, bi-stretching, non-woven non-woven meltblown cloth, laminating film composite, recycled granulation environmental protection recycling system and coating machine manufacturing system. The center and production department provide a full set of professional technical solutions to meet the special needs of each customer. Among them, the biaxially oriented film manufacturing system includes: BOPP biaxially oriented film manufacturing system, PVC biaxially oriented shrink film production line, PET biaxially oriented film production line, BOPA biaxially oriented film production line, BOPA biaxially oriented film production line, etc.
Company Address: No. 11, Kaifeng Road, Moling Street, Jiangning District, Nanjing City, Jiangsu Province