Tyvek® desiccant sachets, that is with Tyvek® outer casing, have a higher cost than the much more common ones in TNT. However they have a series of characteristics that make them much more suitable in particular cases, for example in high fashion (thanks to the clearly superior aesthetic appearance), in the optical, food and pharmaceutical industries (thanks to the special technical characteristics of this fabric).
But let’s go with order. In this article we will see, in particular:
- What are the technical limits of the normal sachets in silica gel or bentonite with TNT casing.
- What the current international regulations say.
- The different sectors in which Tyvek® bags are used, and why.
- Finally, we will also explain why Tyvek® desiccant sachets cannot be regenerated.
The TNT problem: dust
Dehydrating products such as the classic silica gel or activated clay – also called bentonite – are widely used in many applications thanks to the total absence of toxicity, ease of disposal and practically universal compatibility with any material, goods or product, even if it comes to direct contact.
We remind you that, due to their function, desiccant sachets cannot be covered with a totally waterproof material, or they could not absorb the humidity of the environment.
This also involves, however, that by nature all TNT dehydrating sachets are characterized by a dispersion of the powders generated by the internal rubbing of the granules. This dust release is almost invisible; to realize it with the naked eye we have to observe sachets of heavier weight in case of falling to the ground, or if they are slammed with force.
However, these minimal powders are present, even if in minute and invisible quantities; in practice, the classic envelope of the sachet, made for example in the common non-woven fabric, is a porous material and does not constitute a sufficient barrier to retain the dust generated by the friction of the various granules of dehydrating material inside the sachet.
The casing which is therefore unable to guarantee total impermeability to dust dispersion is defined as “Material A” according to DIN standards.
These powders that inevitably disperse in the external environment are inert, but they are still considered a contaminated element in particular applications where even the smallest foreign particle is not allowed.
When we talk about particularly delicate uses such as in the pharmaceutical, optical-photographic or food industry, there is therefore the need to resort to casings that give greater security guarantees, guarantee of “Dispersion 0” of the powders: resorting to Tyvek® desiccant sachets .
It didn’t end there, though. Tyvek® finds wide application even when the company that uses desiccant sachets wants to guarantee a better aesthetic impact. Both the texture of Tyvek®, in fact, and its yield as a support for printing are definitely more pleasant and aesthetic than the economic TNT.
Dupont Tyvek®® style 4058 B sachets and regulations
At the legal level, reference can be made to the German DIN 55473 directives to be sure of having a product that can circulate freely throughout Europe and beyond.
Special casings are needed which, in relation to the DIN 55473 standard, are certified as “dust free” or able to guarantee total impermeability to dust dispersion; not by chance we also speak of “zero dispersion”. According to the legislation, the envelope that has these characteristics is called “Material B”.
The desiccant sachets must therefore be able to let in moisture (so that they are absorbed), but they must not let out anything, not even the smallest fragment of dust. This task is perfectly accomplished by Tyvek®, whose full name, to be precise, is Dupont Tyvek®® style 4058 B.
Tyvek® sachets can be produced in any weight and are of particularly high quality not only because they are certified for zero dust dispersion, but also because they are particularly robust and more resistant than normal silica gel sachets with non-woven fabric casing ( TNT).
Another great peculiarity of Tyvek® compared to the common TNT is the possibility to customize the envelope with logos or writings characterized by a very full and excellent quality print. Compared to TNT, Tyvek® is a material that has an intense white color and a particularly smooth surface. It is an excellent support for ink printing and allows you to create sachets with a print that has nothing to envy to printing on paper as the ink is imprinted on a material that keeps it stable (the print never gets discolored) and particularly full and evident, with excellent definition.
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Our company, Disidry Silica Gel, supplies a wide range of Tyvek® desiccant sachets, both available for immediate use and customizable (for weight, measurements and prints) to order.
Our Tyvek® sachets cover a wide range that starts from the special Microbags from 1 gram up to the 30 gram weight. We commonly have In Dupont Tyvek®® sachets available in grammages of 1 gram, 2 grams, 5 grams and 30 grams.
On customer specification we can make Tyvek® any kind of weight in the catalog. Customization is not limited to the use of silica gel as a dehydrating material: even sachets in activated clay (or bentonite) can be packaged in Tyvek®.
The needs of the pharmaceutical and optical-photographic industry
Let us now look at the needs of those sectors which, due to regulations or commercial needs, need dehydrating sachets with safer or more performing envelopes than the common ones.
The pharmaceutical industry makes extensive use of dehydrating products as many active ingredients and drugs are extremely sensitive to humidity.
A promiscuous packaging of the dehydrating product is often required, which must be in direct contact with the drug that we expect to have in the solid state (tablets or powders). It is therefore often necessary to study ad hoc solutions to be sure of complying with all the regulations and requirements related to the product to be preserved.
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The optical and photographic industry produces components that are very sensitive to humidity, not only in terms of electronics but above all in terms of lenses. It is therefore natural that, in order to protect particularly high quality lenses (from the normal camera to the optical group of a telescope), it is necessary to resort to desiccant sachets that offer absolute certainty on the total impermeability to dust. In fact, the smallest grain of silica gel powder that could settle on the lenses would lead to potential optical aberrations in the case of particularly powerful lenses!
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Print with other precision: Tyvek® sachets in high fashion
It is not just a matter of regulation: the desiccant sachets in Tyvek® can be chosen, as already mentioned, also for their clearly superior aesthetic performance.
In this regard, it is interesting to note that it is still possible to use printing techniques and personalization of very different sachets, which lead to a further subdivision of the final product.
In particular, there is a substantial difference between sachets produced with so-called “continuous” printing and those coming out of single printing, piece by piece.
It is important to reiterate that this time the difference is only aesthetic: both types are produced with the same material and classified as a “Material B” casing with zero dust dispersions according to DIN standards.
► Tyvek® sachets with continuous printing
Continuous printing is a faster printing method and therefore represents a more economical printing process. In practice, the ink printing – whether written, warnings or logos – are imprinted on the envelope of the sachet when they are still all joined together in a single ribbon. This printing does not allow an exact centering: the writings or the logo may be off-center or you can have a repetition of the writings in series on the same sachet.
This type of printing is acceptable in all those contexts in which the sachet must have certain technical requisites – such as the certification of 0 dust dispersions – but it is also not required an aesthetic care or a certain level of presentability of the sachet itself.
► Tyvek® sachets with single print
In sectors where it is necessary to introduce a sachet of silica gel in association with high-quality or high-value products – think above all of the entire fashion or leather goods sector – the guarantee of a sachet made of Tyvek® with zero dust dispersion it’s more than enough.
The sachet must be personalized with a print and above all with a company logo that must be presented with a high aesthetic quality: the same sachet bears in fact a brand that is an integral part of the entire product.
This is why a continuous printing is no longer required, but a more accurate print and therefore exactly centered in the body of the sachet. This type of processing, which involves precisely a print centered on the sachet, is a more refined process as it is slower and more expensive: just think of what it means to print individually, piece by piece, lots composed of thousands of pieces .
This type of printing is acceptable in all those contexts in which the sachet must have certain technical requisites – such as the certification of 0 dust dispersions – but it is also not required an aesthetic care or a certain level of presentability of the sachet itself.
Tyvek® sachets in the food industry
The use of desiccant sachets in combination with loose food is permitted provided certain requirements are met.
► First of all, the sachet must absolutely be in a material B envelope. Although silica gel is an inert material, the smallest trace of dust is still considered a contaminate which must not come into contact with food or food.
► In addition to that the printing must be done with special biocompatible inks. The sachet with these characteristics and with the warnings prescribed by the European standards marked with the print “do not eat” is therefore compliant with mixed use with loose foods.
In addition to these two fundamental requisites that characterize the sachet for food uses, the permitted use must also be specified on the sachet (special certifications and safety guarantees are required before putting the sachet in contact with any type of bulk food). The use of desiccant sachets in combination with loose food is permitted as long as certain requirements are met.
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The silica gel sachet can be put in direct contact only with dry foods that are not characterized by fats of any kind (oils, butter, etc.). In other words, the envelope of the sachet which comes into contact with this loose and unpackaged food must not in any way remain wet or become greasy, but must remain dry and indifferent. It must not be altered by any substances that may impregnate the casing and therefore alter or nullify the Tyvek® dust resistance.
Regenerate Tyvek® desiccant bags
As for regeneration, the bags in material B cannot be regenerated (neither those in Tyvek®, nor others). Tyvek® and other type B materials represent an unbeatable barrier even for steam, not just dust.
You can try: if you introduce Tyvek® sachets that have already absorbed moisture inside an oven, the heat applied will turn the water that has accumulated in the crystals of the dehydrating material inside the sachet into steam.
However, this accumulation of steam will not be able to pass through the pores of Tyvek® to disperse outside. The sachet will therefore tend to swell exactly like a balloon, until it reaches the breaking of the envelope itself.
We remind you that we at Disidry are always at your disposal to help you find the best solution for your needs for preserving and controlling the humidity of products, environments and industrial plants. Contact us for any question
