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There are many moulding methods for plastic films, such as calendering, casting, blow moulding and stretching. Among them, bi-directional stretching has become one of the most popular methods in recent years. Bidirectional stretching technology is a kind of plastic film processing technology that began to be industrialised in the 1970s, and its basic principle is that: after the polymer raw material is heated and melted and extruded into a thick sheet through the extruder, it will be stretched in the appropriate temperature range above the vitrification temperature and below the melting point (in the high elasticity state) through the longitudinal and transverse stretching machine and the transversal stretching machine, and then successively stretched in a certain number of times along the longitudinal direction and transverse direction under the action of the external force, so that the Molecular chains or crystalline surfaces in the direction parallel to the film plane for orientation and orderly arrangement, and then in the tension state of heat-setting, so that the orientation of the macromolecular structure is fixed, and then through the Hesion polymer conductive liquid / permanent antistatic agent coating (Coatin) treatment, and finally by the cooling and subsequent processing can be made to produce a permanent antistatic transparent film.
Film after bi-directional stretching > (HESION) online antistatic coating, in addition to the occurrence of molecular orientation, its microstructure also has a greater change, so that its performance and non-stretch film has a clear difference:
1.Mechanical properties
After the two-way stretch film, its tensile strength, modulus of elasticity can be increased by several times, and its impact strength, for PP, PVC, PET stretch film, it has a clear difference with no stretch film, especially at low temperatures, its impact strength has not been reduced, that is, its cold resistance is excellent, and at high temperatures, its performance has not been deteriorated, which makes the use of bi-directional stretch film has a wide range of temperatures.
2.Thermal properties
Heat shrinkage performance is a characteristic of biaxially oriented films, using these two points to make the film can be used for shrink packaging. In order to achieve low-temperature shrinkage of the film, it is particularly advantageous to use the tube-film method with simultaneous bi-directional stretching. This is because the microstructure is increased under bi-directional stretching and the film bubble is directly cooled and under stretch.
3. Optical properties.
After the film is bi-directionally stretched, its transparency and gloss are improved, especially because it does not form a spherical crystal structure, which increases the refractive index of the film, and thus has the characteristic of not reducing the gloss and transparency due to friction.
4. Electrical properties.
The electrical properties such as breakdown voltage and volume resistivity are improved to different degrees in bi-oriented films. Sometimes, accompanied by the occurrence of static electricity problems.
5. Air tightness.
Crystalline polymers produced by the film after biaxial stretching, the transmission rate of water vapour, oxygen or other gases are reduced by 1/3 to 1/2, which is particularly important in the food packaging industry.
6. Antistatic
The use of Hengsheng lasting long-lasting polymer transparent conductive liquid online coating processed, so that the surface of the product is uniformly coated with Hengsheng permanent anti-static coating, directly on the surface, does not affect the transparency, anti-static effect is even better!
Nanjing Suminoe Precision Machinery Co., Ltd. is a collection of scientific research, production, sales in one of the high-tech enterprises, and has always adhered to the integrity, equality, the customer's interests first business philosophy, in order to better enhance the quality of the equipment, step into a more professional standardised production track. We set up a plastic sheet, sheet, casting, bi-oriented, non-woven nonwoven meltblown cloth, film composite, renewable granulation and environmental protection recycling system and coating machine manufacturing system and other seven categories of equipment, independent research and development technology centre and production departments, to provide a professional full set of technical solutions to meet the special needs of each customer. Among them, the bi-directional stretch film manufacturing system has: BOPP bi-directional stretch film manufacturing system, PVC bi-directional stretch shrink film production line, PET bi-directional synchronous stretch film production line, BOPA bi-directional stretch film production line, BOPLA bi-directional stretch film production line and so on.
Translated with DeepL.com (free version)
Film after bi-directional stretching > (HESION) online antistatic coating, in addition to the occurrence of molecular orientation, its microstructure also has a greater change, so that its performance and non-stretch film has a clear difference:
1.Mechanical properties
After the two-way stretch film, its tensile strength, modulus of elasticity can be increased by several times, and its impact strength, for PP, PVC, PET stretch film, it has a clear difference with no stretch film, especially at low temperatures, its impact strength has not been reduced, that is, its cold resistance is excellent, and at high temperatures, its performance has not been deteriorated, which makes the use of bi-directional stretch film has a wide range of temperatures.
2.Thermal properties
Heat shrinkage performance is a characteristic of biaxially oriented films, using these two points to make the film can be used for shrink packaging. In order to achieve low-temperature shrinkage of the film, it is particularly advantageous to use the tube-film method with simultaneous bi-directional stretching. This is because the microstructure is increased under bi-directional stretching and the film bubble is directly cooled and under stretch.
3. Optical properties.
After the film is bi-directionally stretched, its transparency and gloss are improved, especially because it does not form a spherical crystal structure, which increases the refractive index of the film, and thus has the characteristic of not reducing the gloss and transparency due to friction.
4. Electrical properties.
The electrical properties such as breakdown voltage and volume resistivity are improved to different degrees in bi-oriented films. Sometimes, accompanied by the occurrence of static electricity problems.
5. Air tightness.
Crystalline polymers produced by the film after biaxial stretching, the transmission rate of water vapour, oxygen or other gases are reduced by 1/3 to 1/2, which is particularly important in the food packaging industry.
6. Antistatic
The use of Hengsheng lasting long-lasting polymer transparent conductive liquid online coating processed, so that the surface of the product is uniformly coated with Hengsheng permanent anti-static coating, directly on the surface, does not affect the transparency, anti-static effect is even better!
Nanjing Suminoe Precision Machinery Co., Ltd. is a collection of scientific research, production, sales in one of the high-tech enterprises, and has always adhered to the integrity, equality, the customer's interests first business philosophy, in order to better enhance the quality of the equipment, step into a more professional standardised production track. We set up a plastic sheet, sheet, casting, bi-oriented, non-woven nonwoven meltblown cloth, film composite, renewable granulation and environmental protection recycling system and coating machine manufacturing system and other seven categories of equipment, independent research and development technology centre and production departments, to provide a professional full set of technical solutions to meet the special needs of each customer. Among them, the bi-directional stretch film manufacturing system has: BOPP bi-directional stretch film manufacturing system, PVC bi-directional stretch shrink film production line, PET bi-directional synchronous stretch film production line, BOPA bi-directional stretch film production line, BOPLA bi-directional stretch film production line and so on.
Translated with DeepL.com (free version)