Desiccant is a hygroscopic substance used as a drying agent.
Desiccants adsorb moisture (water vapor) in the air and lower the relative humidity so as to avoid condensation in a closed environment. They facilitate low humidity and accordingly keep products and goods dry during transportation and storage.
Silica gel and bentonite clay desiccants are two of the most widely used desiccants in various industries and applications.
Bentonite clay has nature-friendly production process having less impact on the environment. It is non-corrosive, inexpensive and effective ( in non-extreme temperatures, up to 49 C). It is widely used especially in industrial settings. It has a high adsorption capacity in conditions having less than 40% relative humidity, which is the case for most packaging environment.
Silica gel can offer dust-free utilization when packed in convenient packaging material. Accordingly, besides its usage in industrial settings, it is also the most preferred desiccant especially in pharmaceutical, food and electronics industries. When there is space limitations, silica gel is again preferred as it has a high adsorption capacity.
There are different type of desiccants such as silica gel, bentonite clay, calcium chloride, molecular sieve, activated alumina, calcium oxide etc.. Each of them has different features, its advantages and disadvantages.
Desiccants are designed to combat the following sources of moisture :
– water vapor in the air inside the package
– moisture on the walls of package
– moisture contained in the material/goods placed in the package
– moisture that enters into the package due to permeation or leakage
It is important to know the size of and type of the container used, the temperature and relative humidity conditions the product will be exposed to during the shipment and storage.
Based on the above factors, the right desiccant can be chosen which can effectively absorb the moisture lowering the relative humidity level to the point to avoid condensation (dew point).
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Most shipping containers experience extremely diverse temperature and climate fluctuations during the course of the voyage. Such changes cause condensation inside the container ultimately raining on the cargo which is referred to as “container rain”. Container rain dripping on the cargo causes corrosion, mold and moisture damage to the products and/or its packaging.
Container desiccant alters the levels of moisture content in the air inside the shipping container by aggressively absorbing water vapor from the air, continuously through all temperature and relative humidity variations. The water vapor is trapped as gel by container desiccant and contained within the desiccant bag until disposal.
Differentiating from the standard industrial use, use of desiccants in pharmaceutical and food industries( in direct contact with medicine and food) requires to comply with the highest quality standards.
In the regard; production in dedicated food/pharmaceutical grade (GMP/clean room/dust-free) workshops, compliance of all used materials (desiccant + its packaging material + printing ink etc..) with FDA and EU relative standards are important points to be taken into consideration.
These are industry standards for desiccant sachets. DIN is the German standard while MIL is the American equivalent of same.
A desiccant unit is the quantity of desiccant that adsorbs at least 6.0 g of water vapor in equilibrium with air at 23 °C (± 2 °C) and 40 % relative humidity. According to DIN 55473-B, weight of 1 unit silica gel is 25g and 1 unit bentonite clay is 33g.
VCI (volatile corrosion inhibitors) create a thin molecular protection layer on metal surfaces preventing the oxygen, moisture and other corrosive elements from attacking the surface of the metal and thus avoid rust and corrosion. When the metal products are removed from packaging, VCIs float away easily thus no cleaning or degreasing is necessary.
VCI technology comes with many advantages, to name a few :
– ease of use
– no hassle to remove coating or rust preventative chemical thus no associated labour and time costs
– also protects the equipment where it is normally impossible to apply liquid based rust preventative
– long shelf and service life
Desiccants work by absorbing the moisture from the airspace inside the sealed container. The level of relative humidity (RH) inside the container directly affects the amount of moisture reacting with the metal surface. When the RH exceeds a certain level ,corrosion may occur. Accordingly desiccant’s role in lowering RH is important. If the new air is allowed to get into the container, the desiccant may get saturated and will no more continue absorption.
VCI technology provides corrosion protection by forming a molecular protective layer on the surface of metals. It offers a robust protection with a long service life. VCI can form a first resistant line of defense against impacts that cause corrosion.
Above two products work independently and are completely different protective packaging products. On the other hand, for many applications, they can well be used together. Desiccants can reduce the amount of moisture VCI will have to combat with.
These terms refer to packaging systems used to extend shelf life, maintain product freshness, avoid damages caused by environmental affects, monitor and display information on quality and safety. These packaging solutions are especially used in pharmaceutical and food industries.
Active packaging covers the packaging products directly interacting with the goods in the pack chemically or biologically. It helps to extend shelf life, prevent microbial and fungal growth while maintaining quality and ensuring safety. Some of the examples are desiccants, oxygen absorbers, ethylene absorbers.
Intelligent packaging stands for packaging integrated with a specific sensor which is able to store information about the historical data throughout the supply chain with regards to freshness, microbial contamination, fungal growth, leakage etc.. Accordingly, it helps to provide information about real shelf life, current state of quality of the product in the pack communicating these information to the customer. Some examples are temperature-moisture indicators, microbial spoilage sensors, physical shock indicators, leakage indicators.