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Problems and solutions in the application of PVC profile protective film
PVC profile protective film is based on plastic film or aluminum-plastic composite material, and is coated with low-viscosity pressure-sensitive adhesive on one side. Attached to the surface of the profile, it can effectively prevent the surface of the profile from being scratched or polluted during extrusion, transportation, window forming, and installation. It appears to profile production, door and window assembly,
And the construction unit has brought great convenience. Since the profile protective film is a relatively new product, there is no national or industry standard yet. There is no unified technical index for the detection and evaluation of product quality.
This brings certain difficulties to the user when choosing to use the protective film. Many profile manufacturers have encountered some problems in the process of use. This article will discuss these problems with you.
1. Degumming problem
Phenomenon: After tearing off the protective film from the surface of the profile, glue traces remain on the surface of the profile. The main reason for this phenomenon is the quality of the protective film itself. First, the pressure-sensitive adhesive used in the protective film does not meet the requirements. The technical requirements cannot be met in terms of formulation and process implementation. The peeling force is greater than the cohesive force; the second is that the corona strength of the base material used for the protective film cannot meet the requirements. Generally, the surface tension of the substrate is required to be between 3840dyn. If it is too small, the peeling force of the protective film will be greater than the adhesive force, resulting in degumming. If such problems occur, it is recommended that the profile manufacturer do the following: Use a clean rag dipped in an appropriate amount of organic solvent such as ethanol, ethyl ester, toluene, etc. to wipe.
This sometimes brings about a problem, that is, the surface finish of the profile will be damaged to a certain extent after wiping with a solvent. The remedy: wipe it with a soft dry cloth several times to restore the finish.
Second, the sticking is not firm
Phenomenon: After the profile is extruded and filmed, the film is not strong, and it is easy to peel off during transportation and window forming, which does not play a protective role. There are several reasons for this phenomenon:
1. After the profile is extruded and before the film is applied, its surface is not clean, such as moisture and dust. Improvement method: After the profiles come out of the cooling and shaping die, try to dry the surface water as much as possible, pay attention not to have too much dust in the workshop, and keep the tractor crawler clean, etc.
2. The pressure of the laminating machine is not enough, or the structure is unreasonable. Solution: Appropriately increase the film pressure; use a special film machine.
3. The viscosity of the protective film is not enough.
4. The tensile stress of the base material used for the protective film is too small, and it is easy to deform, or the rotating part of the film applicator is inflexible, causing the film to be stretched too much and deformed during the application process. After sticking to the profile surface, the film retracts due to the stress generated by the stretching. When this retraction force is greater than the peeling force, the film peels off automatically. In this case, BOPP, PET or composite protective film with larger tensile force can be used instead; in addition, the rotating part of the film laminating machine should be lubricated frequently to make it rotate flexibly.
Three, the two ends are raised
This phenomenon mostly occurs on profiles with aluminum foil films. It is mainly manifested in the lifting of the protective film at both ends of the profile. The main reason is that during the compounding process of the aluminum foil film, the tension of the BOPP and PET layers is inconsistent, and the tension of the BOPP layer is too large. It is not recommended to use this membrane in areas with high ambient temperature and large sandstorms.
4. Difficulty or unable to peel off the film
Phenomenon: After the doors and windows are installed, when the protective film is removed, it is found that the film cannot be peeled off or it is difficult to peel off.
There are two reasons: First, the quality of the pressure-sensitive adhesive used in the protective film is unqualified. The pressure-sensitive adhesive used in the protective film is a special pressure-sensitive adhesive, which can produce an appropriate peeling force with the surface of the product, making the protective film easy to apply and peel off.
However, at present, many manufacturers have not mastered the production technology of this pressure-sensitive adhesive, and only made some improvements to the pressure-sensitive adhesive for ordinary adhesive tapes, and even used it in the production of protective films without improvement. Of course the consequences are unimaginable. In addition, after the doors and windows are installed, they are exposed to ultraviolet rays in the sun for a long time, and the protective film substrate is aged, and the strength is reduced and it is easy to tear, which will also cause this phenomenon. Therefore, it is recommended that the construction unit tear off the protective film in time after the house decoration is completed.
5. There are traces of protective film on the surface of the profile
Generally, there are two situations: one is that the handwriting on the surface of the profile is black; the other is that the handwriting is the color of the words on the protective film. For the first case, there have been articles published in many journals. Most opinion sees it as a chemical change. This chemical reaction must meet certain conditions to occur: moisture, visible light, unstable TiO2. If the above situation occurs, it is recommended to replace the type of protective film or choose PE two-color film and aluminum foil film with good light-shielding properties.
For the second case, it can be definitely considered that the ink of the protective film has migrated. Due to the breakdown of the inner composite layer of the protective film during the corona process. After the glue is applied, it is attached to the surface of the profile. After a period of time, the ink will migrate to the surface of the profile through the composite layer and the adhesive layer, resulting in the writing on the profile. In order to verify this phenomenon, the author has done many experiments, selected profiles and protective films from different manufacturers (the same batch of samples that had the printing phenomenon), and put them under a 250W UV lamp for 8 hours. Printing phenomenon. Later analysis showed that the filming conditions during the test were different from those in the production process, and the printing phenomenon reported by users mostly occurred on one or several fixed extrusion equipment, which was not common. The issued printing phenomenon may have a great relationship with the profile extrusion process conditions. An ideal solution to this problem has not yet been found. In this case, it is recommended to use
PE two-color film, aluminum foil film, etc.
