Influence of friction coefficient of the hottest B

2022-08-15
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Influence of the friction coefficient of BOPA film on quality

release date: Source: packaging frontier editor: litchi browsing times: 4929 copyright and disclaimer

core tip: the friction coefficient of film is divided into dynamic friction coefficient and static friction coefficient. Static friction coefficient refers to the ratio of the maximum resistance of two contact surfaces at the beginning of relative movement to the normal force vertically applied to the two contact surfaces. The dynamic friction coefficient refers to the ratio of the resistance when two contact surfaces move relatively at a certain speed to the normal force applied vertically to the two contact surfaces

[China Packaging News] generally, the friction coefficient s of b0pa film treatment surface is 0 4~0. 7

the friction coefficient of thin films is divided into dynamic friction coefficient and static friction coefficient. Static friction coefficient refers to the ratio of the maximum resistance of two contact surfaces at the beginning of relative movement to the normal force vertically applied to the two contact surfaces. The dynamic friction coefficient refers to the ratio of the resistance when two contact surfaces move relatively at a certain speed to the normal force applied vertically to the two contact surfaces

in the production process of film, the friction coefficient of plastic film is an important technical index. On the one hand, it and the anti adhesion performance of the film together become the quantitative evaluation index of the opening of the plastic film. On the other hand, it can be used as one of the reference data of the running speed, tension adjustment and wear in the running of the automatic packaging machine. The size of the friction coefficient can be controlled by the selection and dosage of additives. For automatic packaging products, the friction coefficient of the side where the film contacts the equipment is 0 25~0. 30 is better. Generally, when BOPA film is used as a printing surface, due to the demand of post-processing and rapid coding, the friction coefficient of the untreated surface of the film should be less than 0.25. If the friction coefficient is too large, the film will have a large resistance to use, and it is easy to break the film and crack. With the increase of additive content in the film, the friction coefficient of the film will decrease and the haze will increase

in the process of printing and aluminizing, there are also certain requirements for the friction coefficient of plastic film. Because of its poor printability, the surface friction coefficient of thin film has a linear relationship with its surface roughness. In a certain range, the greater the surface roughness, the smaller the friction coefficient. In other words, reducing the friction coefficient of the film surface is beneficial to printing and aluminizing, to increase the joint surface between them and plastic film, and to improve the adhesion between them. The friction coefficient is also adjusted by using additives. Therefore, the friction coefficient between the film surface and the metal (stainless steel) surface must be tested before the film leaves the factory. In case of high humidity and high temperature weather or high-speed coding products, the BOPA film surface requires not only low moisture absorption but also low surface friction coefficient. The surface friction coefficient of BOPA ultra-high smooth film can generally be controlled between 0.15~0.25

the reason why the friction coefficient of the film continues to decline is that the lubricant continues to migrate to the surface of the film and covers more and more areas on the surface of the film. If the lubricant that has migrated to the surface of PE film disappears or decreases for some reason, the result will be an abnormal increase in the surface friction coefficient of PE film

take the composite film of bopa/pe structure as an example. For the composite film in the winding state, the inner surface of BOPA film is bonded with the composite surface of PE film through the action of adhesive, while the outer surface of BOPA film is tightly close to the thermal surface of PE film under the action of winding tension. Oleic amide and Erucic amide can be used for both PE film and PP film. Assuming that 1000 ppm of smoothing agent is added to the heat sealing layer of PE film, that is, the core layer and composite layer of PE film do not contain smoothing agent, then the smoothing agent in the heat sealing layer will slowly migrate to the surface of the heat sealing layer, the composite layer and its surface. When BOPA film is processed, amide smoothing agents are not used. Therefore, the smoothing agents that migrate to the surface of the heat seal layer may migrate to the surface and interior of BOPA film. On the one hand, the slippery agent migrating to the composite surface of PE film will reduce the peel strength, on the other hand, it will reduce the number of effective slippery agents on the thermal surface of PE film, which will lead to the increase of the friction coefficient of the thermal surface; On the one hand, the amount of effective lubricant on the thermal surface of PE film will be reduced, which will lead to the increase of the friction coefficient of the thermal surface of PE film, and on the other hand, the friction coefficient of the outer surface of PA film will be reduced

in general printing environment, the measuring range of pressure testing machine is also different. Temperature has a great impact on the friction coefficient, because under high temperature conditions, the thermal movement ability of macromolecules of polymer materials is strengthened, the activity speed is accelerated, the molecular gap becomes larger, and the friction coefficient of thin films will change with the change of surface properties. In addition, the smoothness of the film is mainly achieved by adding a smooth agent. After the film is formed, especially the smooth agent of PP and PE film migrates from the film to the surface and accumulates into a uniform thin layer, which can significantly reduce the friction coefficient of the film and make the film have a good smooth effect. Most of these additives that won't pollute the car are inorganic polymer materials (such as amines or esters), which have poor compatibility with resin. Generally, from 30 ℃, the commonly used lubricants have approached their melting point and become bonded, and the friction coefficient of the film rises sharply. The force applied during the test will fluctuate greatly, showing an intermittent sliding or bonding effect. 2 ⑶ manufacturers or brand enterprises are sure to have good results. If the content of smoothing agent is too high, it will also affect the printability of the film, which is extremely detrimental to printing. Therefore, the film surface should have appropriate smoothness to ensure its smooth high-speed printing. Under normal temperature, the dynamic friction coefficient of the untreated surface of ordinary BOPA film surface is generally required to be between 0.2~0.4 (excluding the film requirements for fast coding). The dynamic friction coefficient of BOPA film corona treatment surface is generally not higher than 0.7, and the probability of failure is less when used

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