Abstract: Air cushion is a widely used buffer packaging material, integrating economic and environmental benefits. Load bearing is an important determinant of its buffering effect. It can realize the data representation of this performance through static compression test and dynamic compression test. Through analysis, it is found that many process parameters and circulation environment of air cushion cushioning packaging, such as the stretchability of film materials, the sealing quality of packaging materials, and the inflation pressure, will affect the bearing capacity and cushioning effect to some extent. Strengthen the experimental monitoring and research on the above factors.
Key words: air cushion cushioning, load bearing, film stretching, sealing quality, inflation pressure
Foreword
In recent years, the rapid development of the e-commerce economy has greatly promoted the geographical circulation of goods. At the same time, the problem of rough handling of transportation has become more and more prominent, and the damage rate of package contents has increased year by year. In the circulation, the cause of damage to the goods mainly comes from the external impact of the loading and unloading and transportation environment. Although the speed changes little, but the action time is short, it will have a large impact on the contents in an instant and cause damage. Therefore, a cushioning material having a suitable cushioning effect is extremely necessary in the packaging process.
Buffer materials have a long history and can be traced back to straw, shavings, paper scraps, etc. As the scope and speed of commodity trading has increased, the category of cushioning materials has been greatly expanded. Today, foaming systems based on foamed plastics, bubble film, paper liner and paper molding have been formed. The foam is light in weight, strong in moisture absorption, inexpensive and good in cushioning effect and vibration absorption performance, but the problems of degradation and environmental pollution remain to be solved. The paper cushioning material is a biodegradable material with a temperature adaptation range wider than that of the foam, but the moisture resistance is not good and the price is high. In this context, it is urgent to seek a new type of cushioning material with uniform economic and environmental benefits, and “air cushion packaging†has emerged.
Air cushion cushion packaging load bearing and verification method
The air cushion cushioning package is a buffering effect of sealing a certain compressible gas in a plastic film bag, and has the characteristics of small volume, light weight, large elasticity, convenient packaging and reusability, and has economic, social and environmental benefits. The cushioning effect of the air cushion cushioning package is the result of the interaction of the gas and the film bag. The gas itself is diffusible, and when it is filled in a plastic film bag, it can quickly fill the entire container, and when it is subjected to external pressure, the gas volume is reduced to absorb the impact energy. The film bag constrains the volume change of the gas and at the same time guarantees the sealing of the gas, and is an important carrying container for the air cushion cushioning packaging material.
At present, there is no uniform standard for the bearing capacity of the air cushion cushioning packaging material, and the buffering curve, including the compressive stress-strain curve and the maximum acceleration curve, are mainly obtained through experiments to verify the cushioning performance of the material to be tested. These tests include static compression test and dynamic compression test, which are based on the national standard GB/T 8168-2008 buffer compression material static compression test method and GB/T 8167-2008 packaging buffer material dynamic compression test method. The so-called static means that the speed of pressurizing the sample on the compressor is very slow, such as 12mm/min, close to the static load. Static compression stress-strain curves, buffer coefficient curves, etc. can be obtained by static compression test to understand the static buffer bearing capacity of the material.
The static compression test process is simple and easy, low cost and short in time. The compression instrument, such as i-Boxtek 1700 carton compression test instrument, is tested with reference to GB/T8168 Method A. Before the test, the air cushion sample was subjected to thickness measurement as the original thickness. The upper plate was gradually increased in load in the thickness direction at a speed of 12.7 mm/min. During the compression process, the instrument system automatically records the compression force and the corresponding deformation amount, and draws three curves of “force value-deformation curveâ€, “force value-time curve†and “deformation amount-time curveâ€. The test was stopped when the compression load increased sharply, and the thickness of the sample after the test was measured after the load was removed for 3 minutes. The compressive stress and compressive strain are calculated according to Equation 1 and Equation 2.
α = P/A ×106 ------------------------------ 1
Εa = (T-T_j)/T ------------------ 2
Where α—compressive stress (Pa); P —— compressive load (N); A —— test sample bearing area (mm2); εa —— compressive strain (%) during method A test; T —— test sample Original thickness (mm); Tj - thickness (mm) of the test sample after the test.
Compared to the static compression test, the dynamic compression test conditions are closer to the actual situation. It uses the weight of the impact tester to impact the sample with a certain impact energy to obtain the maximum impact acceleration. By changing the drop height and weight of the weight, a series of maximum accelerations are obtained, so that the cushioning performance curve of the cushioning material can be obtained. According to the requirements of GB/T 8167, it is necessary to test the test data under different heights and thicknesses several times. Therefore, the dynamic compression test has the disadvantages of long time, high cost and complicated process.
Load bearing impact analysis and inspection method for air cushion cushion packaging
The various process parameters and circulation environment of the air cushion buffer packaging, such as the stretchability of the film material, the sealing quality of the package as a whole, the inflation pressure, etc., will affect the bearing capacity and the buffering effect to some extent.
Air cushion cushioning film tensile properties
The process in which the air cushion is deformed by the impact is also the process of stretching the air cushion film material. The film is stretched to fracture and can be considered as two stages: a linear elastic zone and a plastic zone. At first, the sample gradually changed from a free state to a tight state, entering the elastic region of the wire, and entering the plastic deformation zone beyond the elastic deformation limit. The film undergoes molecular orientation, rearrangement, and slip along the direction of external force, yielding occurs, the original configuration is destroyed, the entire crystal mode is rearranged, and the crystal region and the amorphous region exhibit a relatively large range of relative movement. In the second stage of plastic deformation, the film molecules not only undergo molecular orientation, rearrangement and slip along the direction of external force, but also break between the main chains of the molecules. The tensile properties of the film are characterized by the maximum stress value that the film material is subjected to before breaking, and is usually tested using a tensile machine. The better the tensile properties mean that the film material has an advantage in carrying pressure, which provides a more reliable guarantee for the cushioning effect of the air cushion.
Air cushion cushioning bag sealing quality
Sealing is the premise and basis for the performance of the air cushion. The sealing performance of the package is mainly reflected in the integrity of the package and the sealing quality of the edge seal. When the edge sealing is in the heat sealing operation, the high temperature treatment will affect the mechanical strength of the material around the sealing edge, such as tensile properties, so the heat sealing edge and its surrounding parts often become the weak point of the air cushion cushion film bag sealing property. When the impact acts on the air cushion, the edge of the film bag is subjected to a strong and unevenly distributed air pressure, and the portion with the lowest compressive strength first has cracks and gas leakage, thereby causing the failure of the air cushion cushioning action. Therefore, the sealing quality of the air cushion cushioning package is judged, on the one hand, the compressive strength of the film bag, and on the other hand, the heat sealing strength of the edge banding.
The compressive strength of the film bag is obtained by an internal pressurization test, also known as a burst test in the industry. The maximum bearing pressure of the film bag can be accurately determined by filling the film bag with a certain pressure of gas until it breaks. In the case of air cushion cushioning packaging materials, the films used are mostly soft and elastic materials, which have excellent stretchability and deformation rate, and will obviously deform with the increase of the filling gas, so that the test of the maximum bearing pressure becomes Difficulties. In practical applications, the air cushion cushion film bag is stuffed between the commodity and the outer package, and is squeezed by the two, and the force is different from the general free expansion. Based on the above situation, it is recommended to introduce a restraint plate test device in the internal pressurization test. As shown in Fig. 1, the sample to be tested is placed between the lower and lower plates of the restraining plate to achieve effective control of the pressure expansion of the film bag and the tensile deformation of the material. The pressure is transferred to the heat sealing edge, thereby greatly improving the uniformity of the pressure application force and being closer to the actual situation.
Figure 1. Constraint plate assembly
The sealing edge heat-sealing strength is measured by a tensile machine, and the material is resistant to separation when the force direction is uniform and the force value is uniform (for example, peeling). The above-mentioned compressive strength test intuitively exposes the weak part of the film bag edge sealing. At the same time, the heat sealing strength parameter can also give specific data evaluation to the firmness of the sealing part, and the two complement each other, which is beneficial to The root cause solves the problem of affecting the quality of the air cushion cushion packaging seal.
Initial air pressure inside the air cushion
There is currently no uniform standard for the initial inflation pressure of air cushion cushioning packages, but different inflation pressures have different buffer loading effects for air cushions of the same specification. The author fills an air cushion with seven bearing chambers into 40 kPa, 60 kPa and 90 kPa, and the chamber thickness is 10 mm. The static compression test is carried out by Method A. The test results are calculated according to Equation 1 and Equation 2, as shown in Table 1.
It can be seen from the above table that as the inflation pressure increases, the load carrying capacity of the air cushion cushioning package is improved. This conclusion is helpful to improve the cushioning performance of the air cushion, and also puts more stringent requirements on the sealing quality and compression resistance of the air cushion film bag. However, it should also be noted that the increase of the inflation pressure needs to be moderate. If it is too large, the air cushion is too hard to act as a buffer, and vice versa, the buffering effect is not obvious. The appropriate pressure is obtained through repeated test data.
to sum up
The air cushion is a widely used cushioning packaging material, which integrates economic and environmental benefits. Load bearing is an important determinant of its buffering effect. It can realize the data representation of this performance through static compression test and dynamic compression test. Through analysis, it is found that many process parameters and circulation environment of air cushion cushioning packaging, such as the stretchability of film materials, the sealing quality of packaging materials, and the inflation pressure, will affect the bearing capacity and cushioning effect to some extent. Strengthen the experimental monitoring and research on the above factors.
EO Sterilizer :
ETO Sterilizer is a key equipment for single-use sterile medical device manufacturers. Ethylene oxide does not damage sterilized articles and penetration is very strong, so EO Gas Sterilization can sterilize most of the articles that are not suitable for general sterilization methods. For example, electronic instruments, optical instruments, medical instruments, books, documents, fur, cotton, chemical fiber, plastic products, wood products, ceramics and metal products, endoscopy, dialyzer and disposable medical supplies, etc.
Advantages of ETO Sterilization Machine:
1. All microbes can be killed, including bacterial spores.
2. Sterilized items can be wrapped and packaged, and they can remain sterile before use.
3. Relatively speaking, Ethylene Oxide Sterilization does not corrode plastics, metals and rubber, and does not make things yellowed and brittle.
4. Irregular objects can be penetrated and sterilized.
5. EO Sterilization can be used for sterilization of articles that can not be soaked with disinfectant, dry heat, pressure, steam and other chemical gases.
Any interest, please kindly let us know at your convenience. We will be on service for you at any time. Looking forward to hearing from you soon to talk more.