Change of surface tension of the hottest film VII

2022-08-12
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Change of film surface tension (VII)

b. the smaller the intensity of corona treatment, the earlier the rebound of film surface tension occurs; However, the higher the intensity of corona treatment, the greater the rebound degree

c. for the same additive, the surface tension rebounds earlier when the proportion is large, but the surface tension rebounds more when the proportion is small

d. additives with strong migration performance will have surface tension rebound, and the rebound degree is large

e. the higher the ambient temperature, the greater the chance of rebound; However, it is difficult to observe the rebound phenomenon when the temperature is low to a certain extent

for this rebound phenomenon, we have made many diagrams about the electrostatic changes on the membrane surface. An example of piece and batch [lot, batch] is listed below. See table 21: test date 5.85.95.105.205.316.186.287.47.10 surface tension 5 three minute attenuation or half attenuation 20.7% 14.2% 16.8% 16.7% 15.1% 25.8% half-life 53.4s half-life 5.3s48.3% film in the production and processing process, especially in the casting and stretching, some low molecular weight substances (including migration additives) will move to the film surface, so the film just produced has a certain anti-static ability, but after being placed for 1-2 days, these components on the surface evaporate, At this time, the migratory components have not migrated out. Do you have any understanding? Come on, so the static electricity on the surface is large. Generally, after a week, part of the antistatic components migrate to the surface, which shows that the static electricity decreases. If the antistatic components migrate quickly, after a period of time, we can measure the electrostatic shutdown period of the film, and the corona also decays with its migration, but when the mobile molecules on the film surface reach a certain concentration, a large amount of volatilization will occur, After volatilization, the film surface will return to a rough surface similar to that after the initial corona, and the antistatic property of the film will be weakened at the same time, which is the reason for the corona rebound

we can also take the corona attenuation of 27.5u light film without migration additive film as an example to prove the reason for the rebound, as shown in the following table:

test date 6.226.256.266.276.287.27.67.97.187.25 corona (dyne) so that we can analyze the 5 cases in which we mainly set parameters for the alarm device, that is, the faster the corona attenuation, the antistatic components will volatilize at the same time of corona attenuation, The film surface with slow decay will form accumulation and volatilization. After that, the corona decays fastest in the first 1-2 days after revitalizing non operating assets, and then decays slowly. The antistatic components have not migrated out in such a short time. The polar groups inside and outside the membrane will not move too fast, so the main reason for the rapid corona decay is the stress recovery process of the membrane itself

6. Conclusion:

after corona testing and analysis of multiple groups of membranes, we know that the change of membrane surface tension is related to corona treatment intensity, production speed, ambient temperature, raw material formula, selection of raw materials and film thickness. This conclusion is drawn from experiments, which may be one-sided. If people from all walks of life have other opinions, it needs to be discussed together. (end)

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