Aluminum plating film composite processing and common problems
Aluminum plating film in the process of processing compound, slightly do not pay attention, it may appear quality problem, such as one of the most common composite products are spot, peel strength, low aluminized layer transfer quality problems.
The probability of these quality problems than plastic/plastic and recruit/plastic composite processing quality problems, it is a question of many flexible packaging manufacturers headaches.
Aluminum plating film composite products produce aluminum plating film composite 'spots' phenomenon produced obvious white or gray spots, the spots in the full version of the ink printing process of composite is the most common, mainly because there are three aspects: (1) aluminum plating film itself is poor quality.
In coating is easy to peel, inks and adhesives its surface height is differ, stick relay at spots in ink layer and coating stick relay is low, the tightness between the layers is poor;
No spots coating has obvious metastases, good tightness between the layers.
Reflective strength, through the aluminized layer to form white or gray spots, the spots extent and ink covering power has very big relations.
Good covering power, light spots;
On the other hand, the spots were serious.
(2) the ink itself less hiding power.
Printing film coating after printing ink layer infiltration by ethyl ester of adhesive, and some could be dissolved, after composite ink layer two-tone, will cause the difference of colour and lustre, form the so-called spots.
(3) adhesive quality is poorer.
Here is not to say that the adhesive itself, but this kind of adhesive for aluminized layer affinity is poorer, especially the OPP printing film and BOPP film and aluminum plating film after close, this kind of adhesive performance is more apparent, mainly because this adhesive can high surface tension, coating, glue coating, 'spot' phenomenon.
At the same time at the beginning of this glue adhesion force is relatively high, poor solvent release, after curing, because of the influence of residual solvents, strength is not the same sticky instead.
After printing film composite ink layer infiltration by residual solvent, may produce spot phenomenon.
In general, the above three reasons of 'spots' phenomenon is more, we can adopt the following measures to eliminate this kind of phenomenon: (1) use the ink with better covering power is to eliminate by the first (1), (2) two reasons for this phenomenon is the most fundamental spots of hall 4.
In addition can be carved deep printing network cable roller, increase the ink layer thickness, but this will increase the cost, for flexible packaging manufacturers, is don't want to use, however, in the absence of other good way to also can consider to use.
(2) using the suitable adhesives used in aluminum plating film is eliminated by the first 3 kinds of reasons for this phenomenon is an effective method of spots.
The adhesives used in aluminum plating film with moderate molecular weight and even, at the beginning of adhesion force is not very high, but the coating performance is excellent, good solvent release.
Good peel strength after curing.
In addition, if there is no better adhesives used in aluminum plating film, deeper network cable roller, can be used to slow down the machine speed at the same time, can help to reduce or solve 'spots' phenomenon.
Aluminized layer 'migration' phenomenon 'migration' aluminized layer is aluminum plating film composite products in interlayer strip, aluminum plating layer most points to other membrane, resulting in decreased peel strength, make the products under the content of the resistance drop, influence the quality of the product.
This is a lot of composite flexible packaging manufacturers often encounter the phenomenon, also it is difficult to solve the problem.
The most used aluminum plating film VMCPP and VM
Corresponding composite membrane structure with OPP/PET, VMCPP, PET/VMCPP, OPP/VM -
PET, PET/VMTET wait for a few kinds.
Also in the process of aluminum plating film production, on the thin film coating a layer of binding material, used to enhance the bonding strength between the aluminum and the film, the stand or fall of this layer coating will also be related to the transfer of aluminized layer.
Aluminized layer 'migration' in addition to the quality of the aluminum plating film itself factors, and the adhesive quality factors.
Ordinary adhesive coating performance is poor, poor solvent release and adhesive solution is very easy to permeate to aluminized layer, and destruction of aluminized layer, lead to aluminized layer 'migration'.
To fundamentally solve the problem of aluminized layer 'migration', we are in a composite process of operation, must pay attention to the following: (1) ensure the quality of the aluminum plating film itself, is the premise to solve the problem of other conditions.
If the poor quality of aluminum plating film itself, so it is a good composite technology and the best adhesive are powerless.
(2) choose a suitable adhesive, this is the most effective way to solve aluminized layer migration.
In the complex, the aluminum plating film to choose larger molecular weight, molecular weight distribution more uniform, solvent release of good and poor performance of coating adhesive.
Although small molecular weight of adhesive, coating performance is good, but strong intermolecular activity, through the extremely thin layer of aluminum coating.
Don't choose large molecular weight, molecular weight distribution is not uniform and the poor solvent release of adhesive, because the solvent itself penetration ability, coating, can also affect the adhesion strength;
At the same time, the molecular weight of adhesive in the process of production, its molecular weight is not necessarily homogeneous.
(3) strengthen the film's softness.
In preparation of adhesive solution, appropriate to reduce the amount of curing agent, the main agent and curing agent of crosslinking reaction degree reduced, thereby reducing the brittleness of film, to keep the good flexibility and stretching resistance, is conducive to the transfer of control of aluminized layer.
At the same time when the glue coating weight is related to the product of peel strength, too little or too much will affect the quality of products;
Too little, can cause composite fastness is small, easy to peel;
Too much, can increase the cost.
With the large amount of coating, completely cure time is long, adhesive molecules have enough activity, to break the bad coating.
(4) control of curing temperature and curing time.
Adhesive shrinkage should force produced by crosslinking reaction time, the migration is aluminum layer, the main factors of low peel strength, under the conditions of guarantee rubber crosslinking, decrease the curing temperature and curing time, to slow the aluminium layer of aluminium composite membrane transport phenomena.
(5) in the process of composite processing, tension control are particularly important, is worthy of note.