Briefly describe the key performances that should be paid attention to in nitrogen-filled packaging testing

Abstract: With the advancement of packaging technology, nitrogen-filled packaging has been widely used in the packaging of food, medicine and other products.
Whether the nitrogen concentration in the packaging can be maintained is one of the key factors determining the quality of nitrogen-filled packaging
.

This paper analyzes the performance indicators that should be focused on the flexible plastic packaging materials used for nitrogen-filled packaging, so as to provide a reference for enterprises to screen nitrogen-filled packaging materials
.

Keywords: nitrogen-filled packaging, flexible plastic packaging materials, nitrogen permeation, oxygen permeation, sealing performance, heat-sealing strength, flexibility The direction of research and development tends to be less additive, green, and pollution-free, and the distribution area is becoming wider and wider, which puts forward higher requirements on the packaging technology of products to ensure that the quality of the products remains intact during the circulation process and shelf life
.

Nitrogen-filled packaging is a packaging technology that replaces the gas in the packaging with nitrogen
.

Nitrogen, as an inert gas, can inhibit the reproduction of microorganisms and has no interaction with product components.
Placing the product in a nitrogen atmosphere can reduce the oxygen concentration in contact with the product, and can inhibit the physiological activity of microorganisms, enzyme activity and fresh commodities.
Respiration intensity, to achieve the purpose of anti-virus, anti-corrosion and preservation
.

In addition, nitrogen-filled packaging can also prevent the product from being squeezed, deformed, broken, etc.
, and can keep the appearance of the product intact
.

However, in order to fully perform the above functions, the packaging materials used should have good properties and keep the nitrogen concentration inside the packaging at a high level
.

For this reason, this paper analyzes the performance indicators that nitrogen-filled packaging materials should focus on
.

l Nitrogen penetration rate Nitrogen penetration rate refers to the amount of nitrogen gas permeating a unit area of ​​material per unit time.
The level of this index value directly affects the rate of nitrogen penetration inside the package.
If the nitrogen penetration rate of the packaging material used is high, If the nitrogen inside the package is dissipated quickly, the package is prone to collapse during the storage and shelf life of the product.
Therefore, a lower nitrogen transmission rate is the basic performance that nitrogen-filled packaging materials should have
.

　　At present, the test method of nitrogen gas permeability of packaging materials is mainly the differential pressure method, which is based on GB/T 1038-2000 "Test method for gas permeability of plastic films and sheets - differential pressure method"
.

l Oxygen permeation rate Oxygen permeation rate refers to the amount of oxygen permeating the packaging material per unit area in unit time.
The level of this performance is closely related to the permeation amount of oxygen in the environment to the interior of the packaging during the storage process of nitrogen-filled packaging.
The higher the permeation rate, the faster the penetration rate of oxygen into the package, which makes the gas composition and content inside the package change greatly in a short period of time, the nitrogen concentration decreases, and the oxygen concentration increases, weakening or even losing the nitrogen-filled package.
It should have the functions of anti-oxidation and anti-mildew
.

Therefore, the packaging material used as nitrogen-filled packaging should have a low oxygen transmission rate
.

　　The test methods for the oxygen permeability of flexible plastic packaging materials include the isobaric method and the differential pressure method.
T 1038-2000 "Plastic Film and Sheet Gas Permeability Test Method Differential Pressure Method"
.

l Heat sealing strength Heat sealing strength refers to the force value required to destroy the heat sealing part of the packaging bag.
The level of this index value reflects the sealing fastness of the heat sealing part
.

There is a lot of gas in the nitrogen-filled packaging, and the extrusion force on the heat-sealing part is large.
If the heat-sealing strength of the packaging bag is low or the heat-sealing is excessive, under the extrusion of the gas or with the extension of the storage time, the packaging will be damaged.
Therefore, good heat sealing strength is a necessary condition to ensure that the nitrogen-filled packaging does not leak and reduce the rate of bag breakage
.

　　Mainly according to the standard QB/T 2358-1998 "Plastic film packaging bags - Test method for heat sealing strength" to test the heat sealing strength of packaging bags
.

l Flexibility In the process of product transportation and circulation, the packaging bag will inevitably be folded, pressed and rubbed by external forces, and the surface of the bag body is prone to creases
.

If the flexibility of the package is poor, the defects at the crease will easily leak under the impact of the gas inside the nitrogen-filled package, resulting in a decrease in the gas inside the package and a change in the gas composition
.

The test indicators of the flexibility of packaging materials are tensile force and elongation at break (tested according to the standard GB/T 1040.
3-2006 "Determination of Plastic Tensile Properties Part 3: Test Conditions for Films and Sheets"), rub resistance ( Tested according to American Standard ASTM F392)
.

l Sealing performance The sealing performance test is whether the package is prone to air leakage
.

Good sealing performance requires that there are no defects on the surface of the packaging bag body and the heat-sealed parts that cause air leakage in the packaging
.

At present, the sealing performance of flexible plastic packaging bags is mainly verified by the negative pressure test, and the standard is GB/T 15171-1994 "Test method for sealing performance of flexible packaging"
.

　　The nitrogen transmission rate, oxygen transmission rate, heat sealing strength, flexibility, and sealing performance listed above are all necessary to ensure the nitrogen volume and concentration in the nitrogen-filled packaging, and give full play to its anti-oxidation and anti-mildew quality preservation effects.
Key performance metrics to focus on
.

In addition, according to the different products to be packaged, the performance indicators of the materials that need to be concerned are also different.
For example, nitrogen-filled packaging materials for dry foods such as potato chips should also pay attention to the water vapor transmission rate, solvent residue, total migration rate, etc.
consumption, heavy metals, permanganate,
etc.