What happened when the stretch film suddenly turned yellow?

After buying the stretch film home, there was no need for a while, but in the case of recent preparations for application, I found that some stretch film actually changed from the original translucent to light yellow, how is it, is it mildew? What is the reason for this situation? Stretch film manufacturers come to give everyone an in-depth analysis of the reasons for it, the content is as follows:

In fact, strictly speaking, stretch film only colorless and color two, the appearance of light yellow is mainly DOV, masterbatch and other preservatives or production process changes, if the tone is light, the stretch rate and self-adhesiveness can be applied, if the color is not of course, the general quality will be very poor.

Stretch film development trend to now the production process has long been very perfect, some manufacturers will try to change the secret recipe to produce different characteristics of stretch film, the key is reflected in three levels: hue, stretch rate and self-adhesiveness, a single color change does not necessarily harm the application of stretch film, to understand that in many cases because of the production and processing settings of the melting temperature is not the same, will cause the transformation of stretch film tone, but not easy to harm the clarity, that is a good stretch film, if the stretch rate and self-adhesive performance is reduced, It is a poor stretch film, which is likely to be mixed with his residue.

If the tone of the stretch film is light yellow, but the clarity, stretch rate, self-adhesiveness have not changed, and there is no odor, it can be applied, if the four index values change, do not use.