| Nanjing Sumino Precision Machinery Co.,Ltd | WhatsApp +8617712413069 Inquire Product information |
- |
- |
- |
The use of plastic films in packaging and industrial applications has continued to grow steadily. Plastic films play a very important role as the demand for increasingly complex products grows and the use of thermoplastics and extruders expands. As a result, increasingly stringent demands are being placed on the functionality and performance of thermoplastic extruders, requiring high levels of machine processing control, labor savings, energy savings, and preventive maintenance features.
1. Overview of stretching machines
In general, there are two processes to produce biaxially oriented films: the stretch process and the double film bubble tubular film process. The stretching process is further divided into the stepwise stretching method (continuous stretching method) and the simultaneous stretching method. These two stretching methods are used independently depending on the properties of the resin used, but the stepwise biaxial stretching method is more commonly used worldwide for production. In general, stepwise biaxial stretching is used for the production of biaxially oriented polypropylene (OPP), biaxially oriented polyethylene terephthalate (OPET), biaxially oriented polystyrene (OPS) and biaxially oriented polyamide (OPA).
The biaxial stretching process was developed in Germany around 1935 and then used in the 1940s for practical OPS film applications, but the real development of biaxially oriented films began in 1952, when Du Pont began manufacturing and marketing OPET films The continuous biaxial stretching process basically consists of machine production direction stretching (MD) and transverse stretching (TD). (TD). To summarize, OPP films are produced through MD stretching followed by TD stretching.OPET films can be stretched in the following three ways:
(1) MD¡úTD single stretching method;
(2) MD¡úTD¡úMD multiple stretching method;
(3) MD¡úTD¡úMD¡úTD multiple stretching method.
2. Polymer treatment
It is very important to reduce the moisture in the raw material to prevent degradation during the PET extrusion process. It is also necessary to partially crystallize the pellets during the drying stage to prevent them from agglomeration. It is also important to mix the pure and recycled material as well as to mix it with the masterbatch.
The belt dryer has the following 3 characteristics:
(1) simultaneous crystallization, drying and mixing;
(2) High thermal efficiency due to shortened drying time and energy saving by the belt blade;
(3) The process from crystallization to extrusion is carried out under vacuum conditions, thus preventing degradation.
Drying system: The antistatic agent, anti-adhesive agent and slip agent required for the finished film are added to the pure PP pellets in the form of masterbatch, while the recycled material and trimmed off edges are fed into the finished product. In addition, the drying method is mostly used for hygroscopic materials.
3. Extrusion process
There are several important conditions required below, which are not only used for biaxial stretch processing, but also for extrusion processing of other films and sheets. The conditions are as follows:
(1) The deviation of the extrusion volume should be on the small side;
(2) A uniform extrusion should be maintained along with effective mixing and melting;
(3) Low temperature extrusion should be used to ensure that the resin does not degrade;
(4) It should not contain air bubbles.
4. Filter and die head
The molten resin extruded from the extruder is fed directly into the die head through the connecting tube. The filter is installed between the extruder and the die head for the purpose of separating impurity particles from the resin. Pressure measuring instruments installed at the front and back of the filter unit are to measure the pressure difference caused by the contaminants. The filter media consists of wire mesh, sintered wire mesh, sintered metal powder and sintered metal fibers. The form of the filter is further divided into cylindrical, rod, disc and so on. Depending on the application, e.g., PET tapes, capacitors requiring high quality, the size of the filter element ranges from a few microns to 10 ¦Ìm or 30 ¦Ìm, while disc-shaped filters using sintered metal fibers as media are also widely used. Sometimes filter replacement is considered an obstacle to continuous film production operations. Since high productivity and quality are required, frequent filter changes can cause a decrease in productivity.
Nanjing Sumino Precision Machinery Co., Ltd. is a high-tech enterprise integrating scientific research, production and sales. We always adhere to the business philosophy of honesty, equality and customer interest first, in order to better improve the quality of equipment and step into a more specialized and standardized production track. We have set up independent R & D technology centers and production departments for seven major types of equipment, including plastic sheet and plate, cast, biaxial stretch, nonwoven nonwoven meltblown fabric, laminated film, recycled pelletizing and recycling systems, and coating machine manufacturing systems, to provide professional and complete technical solutions to meet the special needs of each customer. Among them, the biaxially oriented film manufacturing systems include: 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, BOPLA biaxially oriented film production line, etc.
1. Overview of stretching machines
In general, there are two processes to produce biaxially oriented films: the stretch process and the double film bubble tubular film process. The stretching process is further divided into the stepwise stretching method (continuous stretching method) and the simultaneous stretching method. These two stretching methods are used independently depending on the properties of the resin used, but the stepwise biaxial stretching method is more commonly used worldwide for production. In general, stepwise biaxial stretching is used for the production of biaxially oriented polypropylene (OPP), biaxially oriented polyethylene terephthalate (OPET), biaxially oriented polystyrene (OPS) and biaxially oriented polyamide (OPA).
The biaxial stretching process was developed in Germany around 1935 and then used in the 1940s for practical OPS film applications, but the real development of biaxially oriented films began in 1952, when Du Pont began manufacturing and marketing OPET films The continuous biaxial stretching process basically consists of machine production direction stretching (MD) and transverse stretching (TD). (TD). To summarize, OPP films are produced through MD stretching followed by TD stretching.OPET films can be stretched in the following three ways:
(1) MD¡úTD single stretching method;
(2) MD¡úTD¡úMD multiple stretching method;
(3) MD¡úTD¡úMD¡úTD multiple stretching method.
2. Polymer treatment
It is very important to reduce the moisture in the raw material to prevent degradation during the PET extrusion process. It is also necessary to partially crystallize the pellets during the drying stage to prevent them from agglomeration. It is also important to mix the pure and recycled material as well as to mix it with the masterbatch.
The belt dryer has the following 3 characteristics:
(1) simultaneous crystallization, drying and mixing;
(2) High thermal efficiency due to shortened drying time and energy saving by the belt blade;
(3) The process from crystallization to extrusion is carried out under vacuum conditions, thus preventing degradation.
Drying system: The antistatic agent, anti-adhesive agent and slip agent required for the finished film are added to the pure PP pellets in the form of masterbatch, while the recycled material and trimmed off edges are fed into the finished product. In addition, the drying method is mostly used for hygroscopic materials.
3. Extrusion process
There are several important conditions required below, which are not only used for biaxial stretch processing, but also for extrusion processing of other films and sheets. The conditions are as follows:
(1) The deviation of the extrusion volume should be on the small side;
(2) A uniform extrusion should be maintained along with effective mixing and melting;
(3) Low temperature extrusion should be used to ensure that the resin does not degrade;
(4) It should not contain air bubbles.
4. Filter and die head
The molten resin extruded from the extruder is fed directly into the die head through the connecting tube. The filter is installed between the extruder and the die head for the purpose of separating impurity particles from the resin. Pressure measuring instruments installed at the front and back of the filter unit are to measure the pressure difference caused by the contaminants. The filter media consists of wire mesh, sintered wire mesh, sintered metal powder and sintered metal fibers. The form of the filter is further divided into cylindrical, rod, disc and so on. Depending on the application, e.g., PET tapes, capacitors requiring high quality, the size of the filter element ranges from a few microns to 10 ¦Ìm or 30 ¦Ìm, while disc-shaped filters using sintered metal fibers as media are also widely used. Sometimes filter replacement is considered an obstacle to continuous film production operations. Since high productivity and quality are required, frequent filter changes can cause a decrease in productivity.
Nanjing Sumino Precision Machinery Co., Ltd. is a high-tech enterprise integrating scientific research, production and sales. We always adhere to the business philosophy of honesty, equality and customer interest first, in order to better improve the quality of equipment and step into a more specialized and standardized production track. We have set up independent R & D technology centers and production departments for seven major types of equipment, including plastic sheet and plate, cast, biaxial stretch, nonwoven nonwoven meltblown fabric, laminated film, recycled pelletizing and recycling systems, and coating machine manufacturing systems, to provide professional and complete technical solutions to meet the special needs of each customer. Among them, the biaxially oriented film manufacturing systems include: 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, BOPLA biaxially oriented film production line, etc.