PET bi-oriented film technology

Various processing techniques have been developed to produce unidirectional and bi-directional stretch PET films. Typical processing includes the following steps:

① Extrusion of PET using a hanger type die.

② Quenching stage;

③Deformation stage;

④ Post-processing stage.

At the beginning of the process, the extruded molten sheet is quenched by immersing it in a water bath. However, the surface of the film products produced in this way can cause defects due to localised boiling water, so the quality of the film was improved by replacing the water with a mixture of 80% glycerol and 20% water. This was followed by quenching with a quench roller (surface temperature 15-18°C). During the process, a locally positioned inert gas stream was added to the upper surface of each side of the molten film, where the film first came into contact with the surface of the quench roll on each side.

After quenching, the film is heated without regard to crystallinity above the T,temperature with a blowing heater or, later, with a quartz electric heater during the forming process. At this stage, the temperature of the thermal operating window is in the range of 80 to 120°C, and the temperature is normally maintained at 80 to 100°C. After softening the sheet is stretched unidirectionally, sequentially bi-directionally or simultaneously bi-directionally, depending on the application.

Designed for simple unidirectional stretching of PET films with a variety of different rollers. The unidirectional stretching system, roller assembly includes low speed rollers, idle rollers and fast rollers. the production process of PET heat shrink film. This film is widely used for packaging of items of various shapes, closing or sealing the item with heat shrink and allowing the package to be placed in an elevated temperature. During the heat shrink film process, the film is stretched up to two times at 80~135°C and the film is cooled down to room temperature under tension.Above 80°C the film produced by this method shrinks by 35% in the TD direction and 15% in the MD direction. At 180 to 200°C, tape films are produced by stretching from about 1.5x to 2x in one direction and heat curing under tension at 190 to 200°C, which produces no shrinkage.

One of the earliest patents for sequential stretching. The softened substrate is first stretched in the width direction and then in the length direction, or the stretching steps are reversed. The temperature of the second stage should be at least the same as that of the first stage, or 5 to 30°C higher than the first stage, but not exceeding 120°C, at which temperature the thermally activated crystals increase. In the processing of PET films for photographic applications, the film is first stretched in the width direction and then in the length direction. After heat curing at about 190 to 200°C, the film is covered with a gelatinous liquid, which is vinylidene chloride.

With regard to continuous synchronised bi-oriented PET film, the equipment for synchronised bi-oriented stretching is a taut frame, where the edges of the extruded film are thicker than the rest of the film, so that the taut frame can hold the film securely. A process for the preparation of an oriented PET film with a de-glossed, writable surface. In the process, a starting amorphous film is stretched to 4x4 at 112°C,producing a glossy surface. The same result is obtained by stretching the film to 2x2,then cooling the stretched film to room temperature, heating and stretching again to obtain a glossy finish.

Nanjing Suminoe Precision Machinery Co., Ltd. is a collection of scientific research, production, sales in one of the high-tech enterprises, has always adhered to the integrity, equality, the customer's interests first business philosophy, in order to better improve 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.