How is PET biaxially oriented film produced?

Various processing technologies are developed to produce unidirectional and biaxially oriented PET films. Typical processing includes the following steps:

①Extruding PET with coat hanger die;
②Quenching stage;
③ Deformation stage;
④Post-processing stage.

At the beginning of processing, the extruded molten sheet is immersed in a water bath for quenching. However, the surface of the film product produced in this way will cause defects due to local boiling water, so a mixture of 80% glycerin and 20% water is used instead of water to improve the quality of the film. Then quench it with a quench roll (surface temperature 15~18°C). During processing, a positioned flow of inert gas is added to the upper surface of each side of the molten film, and the film first contacts the surface of the quench roll on each side.

After quenching, if the crystallinity of the film is not counted, use a blower heater above T, or use a quartz electric heater in the subsequent forming process. At this stage, the temperature of the thermal operating window is 80~120℃, and the temperature is usually kept at 80~100℃. After the sheet is softened, it will be uniaxially stretched, sequentially biaxially stretched or simultaneously biaxially stretched, depending on the application. Stretching method.

The design of simply uniaxially stretching the PET film with various rollers. In the unidirectional stretching system, the roller assembly includes a low-speed roller, an idle roller and a fast roller. The production process of PET shrink film. This kind of film is widely used in the packaging of various shapes of articles, and the articles are closed or sealed by heat shrinkage, and the packaging can be placed in a heated state. During the processing of the heat shrinkable sheet, the film is stretched to 2 times at 80~135℃, and the film is cooled to room temperature under tension. Above 80℃, the film produced by this method shrinks by 35% in TD direction and 15% in MD direction. At 180~200℃, the production of tape film is stretched from about 1.5 times to 2 times in one direction. Under the action, the heat curing temperature is 190~200℃, so that no shrinkage will occur.

One of the earliest invention patents related to sequential stretching. The softened substrate is first stretched in the width direction and then stretched in the length direction, or the stretching steps are reversed. The temperature of the second stage should be at least the same as the temperature of the first stage, or 5-30℃ higher than the first stage, but not more than 120℃. At this temperature, the heat activated crystals increase. When processing PET films for photography, they are first stretched in the width direction and then stretched in the length direction. After heat curing at about 190~200℃, the film is coated with a layer of gel liquid, which is vinylidene chloride.

Regarding the continuous simultaneous biaxial stretching of PET film, the synchronous bidirectional stretching equipment is a stretcher. The edge of the extruded film is thicker than other places, so the stretcher can hold the film safely. A process for preparing oriented PET film with surface delustering and writing. During this process, the amorphous film was initially stretched to 4x4 at 112°C, creating a shiny surface. Stretching the film to 2x2, cooling the stretched film to room temperature, heating and stretching again to obtain gloss, the same result can be obtained.

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 first. 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 types 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 complete 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.

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