On the corona value test of film surface

Contact letter

Subject: Corona value of film surface

1、 Definition of wetting tension (Corona value)

It refers to that when the plastic surface is just completely wetted by the liquid (that is, the contact angle is equal to zero), the surface tension of the liquid is defined as the wetting tension of the plastic. At present, the film is mainly treated by EDM to improve the wetting tension of the film, so it is commonly known as corona value.

2、 Test of corona value

Simplified test method: place the sample in the test environment [in the air-conditioned environment in summer (about 25 ℃) / indoors in winter (about 15 ℃)] for about 5 minutes, and test it with the corresponding corona pen (Sherman corona pen in Britain is recommended). The painted test solution does not shrink into water droplets for 2 seconds or nearly 2 seconds, that is, it is judged to meet the standard of the corresponding value.

Strict test method: according to gb/t 14216-2008 determination of wetting tension of plastic films and sheets.

3、 Testing in actual production

In most factory tests, simplified corona pens are used for testing:

Due to different corona pens (differences in the use time of the same kind of corona pen), different film storage and testing environment, the test effect will be different to varying degrees. If it is marked with non rapid shrinkage, it can meet the requirements of the corresponding corona value, and the value detected by the corona pen is 1-2 dyne lower than the actual corona value of the film itself..

Suggestions on the service time of corona pen: the corona pen should be used for frequent detection and should be updated every three months.

Annex: gb/t 14216-2008 determination of wetting tension of plastic films and sheets

It is hereby explained!