This is a well-known proverb, such as industry. Industry is also an indispensable industry to promote social development, and products must be needed in the industry to promote the development of social life. , The production equipment of cast film includes extruder, machine head, air knife, cooling roll, corona treatment roll, traction roll, winding device, trimming and recovery system. This article mainly introduces the extruder, head, cooling Three kinds of rolls. Today I will introduce three main production equipment and characteristics of cast film.
Casting CPP film production process flow is divided into eleven steps
Resin → extrusion melt plasticization → T-shaped head extrusion → casting → cooling roller setting → corona treatment → traction → winding → storage natural shrinkage → slitting → finished product.
Compressed air blows the cast film to the surface of the cooling casting roll and adheres to the cooling roll to improve the cooling effect. The two sides of the film are further cooled by two cold rolls. The cooling of the cast film is more sufficient, so the production speed is faster than blow molding The method is higher, which can reach more than 60 ~ 100m / min, which is 3 ~ 4 times the production speed of blown film.
The production equipment of cast film mainly includes extruder, machine head, air knife, cooling roll, corona treatment roll, traction roll, winding device, trimming and recovery system.
- Three main production equipments for cast film
- Extruder
Single-screw extruder is generally used for cast film. The screw for polypropylene has a diameter of 90 ~ 200mm, L / D = 25 ~ 33, ε = 3.5 ~ 4, the structure is abrupt, and it can be equipped with a mixing head; the screw for polyethylene , Diameter 90 ~ 150mm, L / D = 25 ~ 28, ε = 3.0, the structure is metering type.
- Machine head
The polypropylene casting film head can be branched or hanger type. The head width is 1.3m, 2.4m, 3.3m, 4.2m. The length of the straight part of the die is L = (50 ~ 80) t ( t is the film thickness), the film thickness takes a large value when the film thickness is small; the lip opening is 0.3 ~ 0.5mm, and the small value is used when the thickness is large. Most of the polyamide casting film uses a branched tube head, and the length of the lip shaping section is longer than CPP It should be longer. Polyethylene cast film mostly adopts branch pipe structure, branch pipe diameter is 30 ~ 50mm, and die lip clearance is 0.3 ~ 1.0mm.
- Cooling roller
The polyethylene and CPP film casting cooling roller is a steel roller with a relatively large diameter, the diameter is 400 ~ 1000mm, and the width of the machine head is increased. The surface of the roller is hard chrome plated and polished to a mirror finish. The roller is double The spiral cooling tube is cooled by cooling water. There are two double-sided cooling rollers, which are used to further cool the two surfaces of the film, which is smaller than the casting cooling roller and has a diameter of 150 ~ 300mm. The surface is the same as the casting cooling roller.
The cooling of polyamide cast film is different from that of CPP film. It is divided into two steps of cooling. The casting roller is an oil cooling roller, and the heated oil is passed through the roller. The temperature of the hot roller is 90 ~ 100 ℃, which is lower than the temperature of the cast film. The roller cools, and the cold roller cools the film to room temperature.
- Features of Cast Film
Cast film has excellent heat sealing performance and excellent transparency, is one of the main packaging composite substrates, used for the production of high-temperature cooking film, vacuum aluminum plating film, etc., the market is extremely optimistic. Moreover, with the domestic cast film The development of production equipment, some of which have reached the international advanced level. Therefore, the threshold for entering cast film production is getting lower and lower. Because of this, some companies are competing to import cast film production lines in order to achieve a one-stop process. The higher the level of pursuit, the better, and aside the market demand and return on investment, this approach will cause a huge waste of resources.
1) The domestic cast film production line can be divided according to the film width: 2500mm, 3000mm, 3500mm, 5000mm, according to the configuration of the extruder can be divided into: three layers, five layers, seven layers.
2) The domestic cast film production line is mainly composed of five parts: extruding part, casting part, corona part, rewinding part, and electronic control part. Among them, the mold part and the extrusion part can be freely according to customer requirements Combination, thus maximally satisfying the different needs of our customers (market).
3) In addition, the design of domestic equipment also closely follows the international advanced level, such as:
A. The unique design of the back device can adjust the pressure of the extruder freely.
B. The unique design of the screw flow channel can be applied to different materials and realize one machine with multiple uses.
C. The flow channel design of the roller has better cooling effect, more stable product quality and higher output.
D. The linear speed of the domestic cast film production line has reached the level of 160m / min–250m / min.
4) Compared with imported equipment, the domestic cast film production line also has the characteristics of high speed, stable performance, environmental protection, and energy saving. The thickness of the product is 0.017mm-0.08mm (the international standard is calculated by 0.025mm).
The above is the relevant introduction about the three main production equipment and characteristics of the cast film compiled by everyone. I hope this knowledge can help everyone. Interested friends can pay attention to this site.