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The influence of the processing technology of CPP cooking membrane

by:LINYANG     2020-03-17
Cooking class quality and performance of the CPP film in addition to the influence of raw materials, the processing technology conditions of choice is a main factor in determining the quality of products. In film processing production, the main process conditions, including processing temperature, cooling roller temperature and drawing speed, winding tension and corona treatment, etc. , in the processing, the process conditions on the performance of the finished CPP cooking membrane has a certain impact. Level 1, the influence of processing temperature on cooking the CPP film flow process, the first parameter is the temperature, the temperature suitability of choice and control, a direct impact on physical and mechanical properties and chemical properties of the film. Type in general, copolymerization polypropylene extrusion temperature under 240 ℃, should according to the characteristics of the material performance in the process of production, strictly control the processing temperature. Level because of the cooking CPP film used for cooking food packaging for high toughness requirements, and ask the film has high impact resistance performance, so the control degree of crystallinity is extremely important. Processing temperatures, can make the T head stretch of melt and cooling roller temperature difference increases, can more effectively reduce the crystallization rate and reduce the degree of crystallinity, increase the transparency of film, and the impact strength and elongation increased, and the heat sealing temperature is reduced, but at the same time, the tensile strength will be reduced. 2, the influence of the temperature of cooling roll cooling roll temperature, directly affect the transparency of the film. Generally, the higher the temperature of the cooling roll, the crystallinity, the greater the transparency of the film the worse. In order to improve its transparency, should strengthen the cooling effect, lower the temperature of the cooling roll, in order to reduce the crystallinity of film. In general, the temperature of the cooling roll selection around 30 ℃. Considering the cooling roll temperature degrees at the same time, the appropriate increase air ventilation rate, but also to improve the transparency of thin film. In addition, the temperature of the cooling roll also has a great influence to the strength of the film. And film thickness and cooling roll temperature has a direct relationship, when the temperature of the cooling roll must, increase the thickness of the thin film can reduce cooling speed, the crystallinity increase inside the membrane, resulting in a decline in the transparency of the film. At the same time, because of the thin film thickness increases, the insufficient cooling, makes the film appear sticking phenomenon, limits the production of thin film speed and output, but increase the thickness of the thin film can improve the impact strength of thin film and improve the safety of the packaging. 3, the influence of the pulling speed in the process of cooking level of CPP film production, drawing speed is one of the most main reasons for the molecular orientation. Melt through T the nose after extrusion, only in a small amount of directional flow direction, under the action of pulling speed, polymer molecules would have a larger on the longitudinal directional role, so that the film of the longitudinal tensile strength increased, but relative elongation will reduce. To reduce the number of vertical and horizontal two to a larger difference, improve the application performance of thin film, processing should be proper control of pulling speed. In addition, the size of the drawing speed, has certain influence on the thickness of the film. In the case of the extrusion velocity, drawing speed, makes the film thickness decreases, the impact on the performance of its use. 4, the influence of winding tension in the cooking class in the CPP film processing, winding tension directly affects the quality of the film. Typically, winding tension is too large, go against the unwinding of the film, film after finalize the design, there will be a cold drawn phenomenon, serious impact on the performance of the membrane, and the winding tension is too small, can bring certain difficulty to cutting, points to cut the tension is difficult to control. So in production, winding tension should be according to the properties of the material, to adjust the proper tension. At the same time, but also the proper adjustment, according to the thickness of the thin film if the film thicker, the winding tension should choose slightly bigger, if the film is thinner, should be appropriate to reduce tension. 5, the influence of corona treatment when cooking the CPP film used as composite film substrate, or used for printing, corona treatment, must be conducted in order to improve the adhesion of printing ink and the composite strength. Under normal circumstances, can meet the requirement of printing and composite membrane, its surface tension must be thirty-eight dyn/cm or more, but after corona treatment, the surface tension of the film would have declined over time. During production, therefore, should make the surface tension of the film is bigger than actual requirements to tension values, to offset due to decline in influence. Surface tension of the drop is mainly associated with the content of raw material of internal low molecular additive. The more general low molecular additive, the surface tension of the greater the fall. Need of actual test to determine the drop in production, to determine the value of the size of the processing. Usually deal with 42 dyn/cm. If the processing degree is too large, the surface oxidation film, film become brittle and thin film mechanical strength decreased. Cooking class CPP film as a kind of packaging film, more and more attention by people, has become the important products in the packaging industry. Although some products processing technology, there is still a gap with foreign, but we firmly believe that as long as constantly explore practice, give full play to the various advantages of domestic equipment, will open a larger market for our film product. Shenzhen lam Yang technology co. , LTD has ten years of experience in film marketing, here, you can find the optimal quality, best service of all kinds of thin film products, welcome the masses of suppliers and manufacturers to inquire and order.
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