The manufacturing process begins with a film of molten polyethylene terephthalate (PET) being extruded onto a chill roll, which quenches it into the amorphous state. It is then biaxially oriented by drawing.
There may some questions about “mylar bags” after you read the above contents. Why the mylar bags we saw in the kitchen are silvery and shiny? The BOPET films are transparent? Why?
Actually, the materials which used to make mylar bags for food storage are BOPET coated with a thin layer of metal, like foil. That is why when you see BOPET separately, it is transparent. But when we use the “mylar bags” for food storage, most of them are the metal effect. A lot of people thought the bags are made by the metal material. but it’s not true, it’s essence is still plastic and transparent.
Aluminized mylar is metalized BOPET, BOPET coated with a thin layer of metal, usually aluminum foil. The metal is heated and evaporated under vacuum.
It offers the glossy metallic appearance of an aluminum foil at a reduced weight and cost.
A lot of films can be coated with metal except mylar, such as PP, CPP, OPP, PVC, PA, PE.
Here is one more question, why need to coat metal on plastic films? Two reasons
Regarding the aluminum mylar, it is aluminum foil laminated with PET films (not the vacuum coated layer), also was named as PETAL
PETAL is much better than VMPET on barrier properties.
See the comparison
Both foil and mylar films are a high tensile strength, that is why these materials can be chosen as packaging bags for food storage.
But what is the difference between foil and mylar film?
Both mylar and foil are showing very good performance on high tensile strength, but the mylar suffers the disadvantage of packing sharp objects, Easy to be pierced. So the engineers laminate the mylar with polyethylene film as a solution.
Another advantage of mylar is high resistance to high temperature, which means this film can be used to produce IC(Electronic components). Besides, Mylar has chemical stability. So it is used in a wide range of applications.
Actually, mylar bags are the packaging bags which made by mylar films, whatever retort pouches, vacuum bags. Mylar bags expand the storage period of food but the cost the much lower than the professional facility of food storage. In most cases, when we talk about “mylar bags”, it means the packaging bags for food storage made by BOPET film, silver & shiny. Google search engine also shows the same result.
Before we talking about this question, we need to know some history of food storage. Food storage is both a traditional domestic skill and, in the form of food logistics, an important industrial and commercial activity. Food preservation, storage, and transport, including timely delivery to consumers, are important to food security, especially for the majority of people throughout the world who rely on others to produce their food. Food is stored by almost every human society and by many animals.
In the past, people store the food with drying, smoking, fermentation, pickling of sugar/ salt/ vinegar, etc. We can find the commonality in the different method.
Mylar bags show a very good performance of barrier to hot, light, moisture, oxygen, oil and smell. If mylar bags work with food grade store bucket and oxygen absorbers, it makes the shelf life much longer than usual.
But in nowadays, vacuum, sterilizing fill, radiation, fast frozen, preservative are more popular for food storage.
Before the industrial revolution, human just store food to avoid a food shortage. But now most the people never worry about food shortage, we can buy any food we need in the supermarket. It seems no need to store food anymore. Actually, more and more people spent less time on cooking because too much work to do. So the food they bought from the supermarket were store in the fridge firstly, mylar bags are still useful for this kind of family.
Mylar bags can be used to store coffee, nuts, cookie, chips, chocolate, and grain. Most of the food or snacks are stored with a short shelf life between 6 months to 2 years. But it is possible to prolong the time to 5 even 10 years if no oxygen and light. It doesn`t make sense to ordinary human than keep the food to such a long time.
Why do we need to do like that?
After all, food is the second most basic human need after potable water. our economy is not always stable and even natural disasters, war or terrorist attack. We need to make sure we have a sure source of food in case of an emergency. So food storage is one of the scientific research projects for government and scientist. The packing material of food is one of the items to be researched and developed in the whole project.
Generally, most of the producer store the food with sealed mylar bags, especially in the three sides sealed mylar bags. But it is only the one style of the mylar bags. We got more options:
More and more merchants choose mylar bags with logo printed for brand expansion and promotion. The price of mylar bags are very friendly and also very easy to operate the packing and delivery. In the meantime, the effect of printing on the mylar is very good which makes the customized printing operated under a very low cost.
Printing on mylar bags is the same as other flexible packing printing, very easy and efficient.
Below is the popular printing options on the market.
Above all the process is available on mylar bags, just different cost.
Of course, it is also possible to replace the packaging printing by means of labels. Suitable for small batch branding packaging customized
Actually, the same whatever flexography or gravure. Just confirm all the details with the engineer who made the printing plate or cylinder. Just a reminder that too much color on the drawing will increase the cost of the cylinder.
Regarding “silkscreen printing”, it is faster and usable than flexography and gravure. But there still some details which need to be paid much attention. The printing area on the bags is limited, it is not possible to print on the whole surface, especially the edge of the bags which is heat sealed.
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