Foaming gas removal method of inner packing material for fruits in aerospace space station

Abstract

The invention discloses a foaming gas removal method for an inner packaging material for fruits in an aerospace space station, and belongs to the technical field of packaging materials for aerospace. The method comprises the steps that firstly, an inner packaging material to be treated is cleaned, the inner packaging material is placed in a vacuum box to be subjected to low-pressure degassing treatment, after treatment is completed, the pressure is slowly increased to the pressure relief pressure in a natural pressure relief mode, and after the pressure relief pressure is reached, a pressure relief valve is opened for pressure relief; and after pressure relief is finished, taking out the inner packaging material, and standing in a ventilation environment to obtain a finished product after standing is finished. According to the method disclosed by the invention, a large amount of foaming gas such as butane in the pearl wool can be removed through repeated decompression and degassing, and finally, the average daily release amount of each kilogram of pearl wool in each cubic meter of space is less than 1ppm, so that the application requirements are completely met. The material subjected to degassing treatment not only can meet the requirement of the aerospace space station for the material attribute of the inner packing material, but also can reduce the pollution of the material to the air in the space station and the harm to the body health of astronauts to the greatest extent.

Description

Technical Field

[0001] The invention belongs to the technical field of aerospace packaging materials, and in particular relates to a method for removing foaming gas from an inner packaging material for fruits in a space station. Background Art

[0002] With the completion of the Tiangong Space Station, my country has achieved the permanent presence of at least three astronauts. Providing sufficient and safe food for astronauts stationed in the space station for a long time is a prerequisite for ensuring the safety of astronauts' lives and health, and even for the smooth implementation of various space missions. With the continuous advancement of my country's manned space technology and cargo spacecraft technology, my country's space food technology is also constantly improving. From mainly carrying high-energy paste-like space food at the beginning to now enabling astronauts to eat fresh fruits in the space station, the variety of space food is constantly increasing.

[0003] The supply of fresh fruit is not only important for ensuring the nutritional balance of astronauts' food, but also plays an important role in keeping astronauts in a positive state of mind for a long time. Since the transportation process of space food is completely different from that of ordinary food, and the cost of space payload is very high, it is very important to ensure the transportation safety of space food and stable storage under special conditions for a long time, especially fresh fruit. Therefore, it is very important to select suitable packaging materials, especially the inner packaging materials that are in direct contact with the fruit.

[0004] Pearl cotton is one of the most common packaging materials. It is widely used in many fields such as electronic appliances, instruments, medical equipment, home appliances, furniture, and gift packaging because of its good waterproof, moisture-proof, shockproof, soundproof, heat-insulating, environmentally friendly and other properties, as well as good plasticity, strong toughness, and strong impact resistance. At the same time, pearl cotton is also the most commonly used inner packaging material for fruits, toys, leather shoes and other products. Because of its many advantages and relatively low cost, pearl cotton is one of the preferred inner packaging materials for fruits used in aerospace.

[0005] Pearl cotton is usually made of polyethylene as raw material. Under certain processing conditions, foaming gas is injected to cause the polyethylene material to foam to form a unique structure with countless independent bubbles inside. Among them, butane and pentane are the most commonly used foaming gases for pearl cotton. Although pearl cotton has many of the above-mentioned advantages suitable for the inner packaging of space food, because it uses foaming gas for foaming, it is easy for the foaming gas trapped inside the material to be continuously released during transportation and storage. Since space is a typical closed space, personnel have extremely strict requirements on the air composition inside it for long-term garrisoning. Obviously, the slow release of foaming gas in the inner packaging material of fruits will undoubtedly pollute the air in the space station, which is not only not conducive to the health of astronauts, but also brings potential risks to the safe operation of the space station.

[0006] In addition, the foaming gas trapped in the tiny bubbles of pearl cotton has a significant impact on the structure and mechanical properties of the pearl cotton itself. Therefore, it is extremely important to minimize the release of foaming gas and reduce the impact on the space station environment while ensuring the mechanical properties of pearl cotton. Summary of the invention

[0007] 1. Technical issues to be resolved

[0008] The present invention aims to solve one of the following technical problems existing in the prior art or related technology:

[0009] The foaming gas in the pearl cotton used as the packaging material for fruits in the existing aerospace is released from the material during use, causing pollution to the air in the space station and endangering the health of astronauts. The problem also arises as to how to minimize the release of foaming gas while ensuring the performance of the pearl cotton.

[0010] (II) Technical solution

[0011] In order to solve the above technical problems, the present invention provides a method for removing foaming gas from an inner packaging material for fruits in a space station, and the specific technical scheme adopted is as follows:

[0012] A method for removing foaming gas from inner packaging materials for fruits in a space station comprises the following steps: cleaning inner packaging materials to be processed, placing the inner packaging materials in a vacuum box for low-pressure degassing treatment, slowly increasing the pressure to a pressure relief pressure by natural pressure relief after the treatment is completed, and opening a pressure relief valve for pressure relief after the pressure relief pressure is reached; after the pressure relief is completed, taking out the inner packaging materials, placing them in a ventilated environment to stand still, and obtaining a finished product after the standing still is completed.

[0013] Preferably, the steps are as follows:

[0014] (1) Clean the dust and debris on the surface of the inner packaging material to be degassed, place the cleaned material in a vacuum box, and set a low-pressure degassing pressure range;

[0015] (2) Start the vacuum pump to reduce the air pressure in the vacuum box, and then perform degassing after reducing it to the low-pressure degassing pressure range; after the degassing process is completed, the vacuum box is naturally depressurized to the pressure relief pressure, and after reaching the pressure relief pressure, the pressure relief valve is opened until the pressure is restored to normal;

[0016] (3) Open the vacuum box, take out the degassed inner packaging material, place it in a ventilated environment and let it stand, and obtain the finished product after the standing time is over.

[0017] Preferably, the inner packaging material in step (1) is pearl cotton.

[0018] Preferably, the low-pressure degassing pressure range of step (1) is 45 kPa-55 kPa.

[0019] Preferably, the pressure relief pressure in step (2) is 75-85 kPa.

[0020] More preferably, the pressure relief pressure in step (2) is 80 kPa.

[0021] Preferably, the temperature of the ventilation environment in step (3) is not less than 20°C.

[0022] Preferably, the standing still in step (3) lasts for 3-15 days.

[0023] (III) Beneficial effects

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention can remove a large amount of foaming gases such as butane from the pearl cotton by repeatedly decompressing and degassing the pearl cotton material, and finally ensure that the average daily release of each kilogram of pearl cotton in each cubic meter of space is less than 1ppm, which fully meets the application requirements. The degassed material can not only guarantee the material property requirements of the inner packaging material of the space station fruit, but also minimize its pollution to the air in the space station and the harm to the health of astronauts.

[0026] Second, in the process of removing the foaming gas in the pearl cotton material, it is found that the removal of the foaming gas will have a great impact on the size and mechanical properties of the material itself. Improper degassing is likely to lead to serious shrinkage of the material size, and the material performance cannot be restored after degassing. To solve this problem, the present application adopts an air pressure of 45-55KPa as the lower limit of the degassing pressure, and in the re-pressurization process, it is selected to slowly recover to 80KPa before decompression, so as to avoid the degassing pressure difference being too large and causing the material structure to be unable to be restored. At the same time, after low-pressure degassing, the material is placed in a place with good ventilation and high temperature, which is conducive to dispersing the foaming gas that continues to be released by the material, and at the same time, it is conducive to air entering the material, and finally realizes the replacement of the foaming gas by air, and maintains the original performance of the material to the maximum extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0028] Figure 1 This is a physical comparison diagram of the degassed pearl cotton and the non-degassed pearl cotton in Example 1.

[0029] The left side is the non-degassed sample, and the right side is the degassed sample. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different embodiments as defined and covered by the claims.

[0031] The reagents, materials, equipment and methods used in the following examples, unless otherwise stated, are conventional reagents, materials, equipment and methods in the art and can be obtained by those skilled in the art through commercial channels.

[0032] The vacuum pump used in the following embodiments is a commercially available microcomputer oil-free vacuum pump, and the vacuum box is a commercially available existing product equipped with a pressure sensor, a pressure relief valve and an observation window. The vacuum box is connected to the microcomputer oil-free vacuum pump, and the opening and closing of the oil-free vacuum pump can be controlled by the microcomputer.

[0033] Example 1

[0034] This embodiment provides a method for removing the foaming gas of the pearl cotton material used for the inner packaging of fruits in the space station, and the specific steps of the method are as follows:

[0035] (1) Cut the pearl cotton raw material with a thickness of 10 cm and a weight of 1 kg, clean the pearl cotton material to be processed, remove impurities such as dust and waste, and then place it in a vacuum box. After closing the vacuum box, set the degassing replacement gas pressure to 45 kPa-55 kPa; wherein 45 kPa is the vacuum pump stop pressure and 55 kPa is the vacuum pump start pressure;

[0036] (2) Start the vacuum pump and perform degassing for 72 hours. During the degassing process, when the air pressure is lower than 45 kPa, the vacuum pump automatically stops. When the air pressure reaches 55 kPa, start the vacuum pump to keep the pressure in the vacuum box between 45 kPa and 55 kPa during the degassing process. When the vacuum box is naturally pressurized to 80 kPa after degassing, start the pressure relief valve to release the pressure.

[0037] (3) Take out the treated pearl cotton material from the vacuum box, place it in a ventilated place with a temperature not lower than 20° C. and let it stand for 10 days to obtain the finished product.

[0038] After the treatment, the undegassed pearl cotton sample and the degassed sample were taken out and photographed to obtain a physical comparison picture, that is, Figure 1 .from Figure 1 It can be seen that the sample volume is slightly reduced after degassing, but the overall change is not significant.

[0039] Example 2

[0040] This embodiment provides a method for removing the foaming gas of the pearl cotton material used for the inner packaging of fruits in the space station, and the specific steps of the method are as follows:

[0041] (1) Cut the pearl cotton material with a thickness of 0.5 cm and a weight of 1 kg, clean the pearl cotton material to be processed, remove impurities such as dust and waste, and then place it in a vacuum box. After closing the vacuum box, set the degassing replacement gas pressure to 45 kPa-55 kPa; wherein 45 kPa is the stop pressure of the vacuum pump and 55 kPa is the starting pressure of the vacuum pump;

[0042] (2) Start the vacuum pump and perform degassing for 72 hours. During the degassing process, when the air pressure is lower than 45 kPa, the vacuum pump automatically stops. When the air pressure reaches 55 kPa, start the vacuum pump to keep the pressure in the vacuum box between 45 kPa and 55 kPa during the degassing process. When the vacuum box is naturally pressurized to 80 kPa after degassing, start the pressure relief valve to release the pressure.

[0043] (3) Take out the treated pearl cotton material from the vacuum box, place it in a ventilated place with a temperature not lower than 20°C for 3 days, and then obtain the finished product.

[0044] Example 3

[0045] This embodiment provides a method for removing the foaming gas of the pearl cotton material used for the inner packaging of fruits in the space station, and the specific steps of the method are as follows:

[0046] (1) Cut the pearl cotton raw material with a thickness of 15 cm and a weight of 1 kg, clean the pearl cotton material to be processed, remove impurities such as dust and waste, and then place it in a vacuum box. After closing the vacuum box, set the degassing replacement gas pressure to 45 kPa-55 kPa; wherein 45 kPa is the vacuum pump stop pressure and 55 kPa is the vacuum pump start pressure;

[0047] (2) Start the vacuum pump and perform degassing for 72 hours. During the degassing process, when the air pressure is lower than 45 kPa, the vacuum pump automatically stops. When the air pressure reaches 55 kPa, start the vacuum pump to keep the pressure in the vacuum box between 45 kPa and 55 kPa during the degassing process. When the vacuum box is naturally pressurized to 80 kPa after degassing, start the pressure relief valve to release the pressure.

[0048] (3) Take out the treated pearl cotton material from the vacuum box, place it in a ventilated place with a temperature not lower than 20°C and let it stand for 15 days to obtain the finished product.

[0049] Example 4

[0050] This embodiment provides a method for removing the foaming gas of the pearl cotton material used for the inner packaging of fruits in the space station, and the specific steps of the method are as follows:

[0051] (1) Cut the pearl cotton raw material with a thickness of 10 cm and a weight of 1 kg, clean the pearl cotton material to be processed, remove impurities such as dust and waste, and then place it in a vacuum box. After closing the vacuum box, set the degassing replacement gas pressure to 30 kPa-40 kPa; wherein 30 kPa is the vacuum pump stop pressure, and 40 kPa is the vacuum pump start pressure;

[0052] (2) Start the vacuum pump and perform degassing for 72 hours. During the degassing process, when the air pressure is lower than 30 kPa, the vacuum pump automatically stops. When the air pressure reaches 40 kPa, start the vacuum pump to keep the pressure in the vacuum box between 30 kPa and 40 kPa during the degassing process. When the vacuum box is naturally pressurized to 80 kPa after degassing, start the pressure relief valve to release the pressure.

[0053] (3) Take out the treated pearl cotton material from the vacuum box, place it in a ventilated place with a temperature not lower than 20° C. and let it stand for 10 days to obtain the finished product.

[0054] Example 5

[0055] This embodiment provides a method for removing the foaming gas of the pearl cotton material used for the inner packaging of fruits in the space station, and the specific steps of the method are as follows:

[0056] (1) Cut the pearl cotton raw material with a thickness of 10 cm and a weight of 1 kg, clean the pearl cotton material to be processed, remove impurities such as dust and waste, and then place it in a vacuum box. After closing the vacuum box, set the degassing replacement gas pressure to 60 kPa-70 kPa; wherein 60 kPa is the stop pressure of the vacuum pump and 70 kPa is the starting pressure of the vacuum pump;

[0057] (2) Start the vacuum pump and perform degassing for 72 hours. During the degassing process, when the air pressure is lower than 60 kPa, the vacuum pump automatically stops. When the air pressure reaches 70 kPa, start the vacuum pump to keep the pressure in the vacuum box between 60 kPa and 70 kPa during the degassing process. When the vacuum box is naturally pressurized to 80 kPa after degassing, start the pressure relief valve to release the pressure.

[0058] (3) Take out the treated pearl cotton material from the vacuum box, place it in a ventilated place with a temperature not lower than 20° C. and let it stand for 10 days to obtain the finished product.

[0059] Example 6

[0060] This embodiment provides a method for removing the foaming gas of the pearl cotton material used for the inner packaging of fruits in the space station, and the specific steps of the method are as follows:

[0061] (1) Cut the pearl cotton raw material with a thickness of 10 cm and a weight of 1 kg, clean the pearl cotton material to be processed, remove impurities such as dust and waste, and then place it in a vacuum box. After closing the vacuum box, set the degassing replacement gas pressure to 45 kPa-55 kPa; wherein 45 kPa is the vacuum pump stop pressure and 55 kPa is the vacuum pump start pressure;

[0062] (2) Start the vacuum pump and perform degassing for 72 hours. During the degassing process, when the air pressure is lower than 45 kPa, the vacuum pump automatically stops. When the air pressure reaches 55 kPa, start the vacuum pump to keep the pressure in the vacuum box between 45 kPa and 55 kPa during the degassing process. After the degassing is completed, when the vacuum box is naturally pressurized to 70 kPa and 90 kPa for different samples, start the pressure relief valve to release the pressure, and release the pressure directly;

[0063] (3) Take out the treated pearl cotton material from the vacuum box, place it in a ventilated place with a temperature not lower than 20° C. and let it stand for 10 days to obtain the finished product.

[0064] Example 7

[0065] This example measures the release of foaming gas in a closed space, the volume loss of the material before and after the treatment, the shrinkage rate of the treated sample, the tensile strength and other mechanical properties of the samples treated in Examples 1-6. Generally, the volume of the pearl cotton material used for the inner packaging of aerospace fruits will shrink during the degassing process, and the volume will recover after the pressure relief, and it can be restored to more than 97% of the original volume, and it is considered to be usable. At the same time, the release of gas per cubic meter per kilogram of sample should be less than 5ppm after standing for 5 days.

[0066] During the measurement, 1 kg of sample was selected and placed in a 1 cubic meter confined space (the space was filled with air at 1 atmosphere, and the foaming gas content was 0). The release time of the foaming gas was 5 days. After the experiment, the air in the confined space was extracted as a test gas sample, and the content of the foaming gas (butane) in the sample was determined by gas chromatography. At the same time, the pearl cotton raw material that had not been degassed was used as a blank control group.

[0067] At the same time, the mechanical properties of the samples prepared in Examples 1-6 were measured according to the standard test methods described in ASTM D1056 and ASTM D3575, specifically, the volume loss, shrinkage (70°C), tensile strength and tear strength of the samples after degassing were measured. The experimental results are shown in Table 1.

[0068] Table 1 Performance measurement results of samples obtained from different embodiments

[0069]

[0070] As can be seen from Table 1, the amount of foaming gas released by the samples obtained in Examples 1-3 after treatment is completely controlled below 5ppm, and the loss of material volume caused by degassing treatment is also less than 3%, that is, the volume of the material can be restored to more than 97% of the original volume after treatment. This shows that under the treatment conditions of Examples 1-3, the removal of foaming gas does not cause unacceptable effects on the applicability of the material. At the same time, the basic technical indicators such as shrinkage, tensile strength and tear strength of the degassed material are close to those of the untreated blank sample.

[0071] However, after changing the degassing pressure, when the degassing pressure is in a relatively small pressure range (Example 4), although the amount of foaming gas released can be controlled within the qualified range, the loss of material volume is relatively large, exceeding 8%, and the material volume is significantly reduced and exceeds the acceptable range. On the contrary, when the degassing pressure is in a relatively large range (Example 5), although the volume loss is reduced, the amount of foaming gas released after the degassing is completed cannot meet the use requirements.

[0072] In the pressure relief stage, when the pressure relief pressure is lower than 75Kpa, the technical effect of the obtained sample is close to that of Example 1-3, except that the volume loss is slightly larger, exceeding 3%. When the pressure relief pressure is higher or directly restored to normal pressure, the foaming gas release of the material is slightly more than 5ppm, and the volume loss increases significantly, and the shrinkage rate of the material also increases significantly.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for removing foaming gas from an inner packaging material for fruits in a space station, characterized in that: Clean the inner packaging materials to be processed, place the inner packaging materials in a vacuum box for low-pressure degassing treatment, and slowly increase the pressure to the pressure relief pressure through natural pressure relief after the treatment is completed. After reaching the pressure relief pressure, open the pressure relief valve to release the pressure; after the pressure relief is completed, take out the inner packaging materials, place them in a ventilated environment and let them stand, and obtain the finished product after the standing time is over.

2. The method for removing foaming gas from the inner packaging material for fruits in a space station according to claim 1, characterized in that: Here are the steps: (1) Clean the dust and debris on the surface of the inner packaging material to be degassed, place the cleaned material in a vacuum box, and set a low-pressure degassing pressure range; (2) Start the vacuum pump to reduce the air pressure in the vacuum box, and then perform degassing after reducing it to the low-pressure degassing pressure range; after the degassing process is completed, the vacuum box is naturally depressurized to the pressure relief pressure, and after reaching the pressure relief pressure, the pressure relief valve is opened until the pressure is restored to normal; (3) Open the vacuum box, take out the degassed inner packaging material, place it in a ventilated environment and let it stand, and obtain the finished product after the standing time is over.

3. The method for removing foaming gas from the inner packaging material for fruits in a space station according to claim 2, characterized in that: The inner packaging material in step (1) is pearl cotton.

4. The method for removing foaming gas from the inner packaging material for fruits in a space station according to claim 2, characterized in that: The low-pressure degassing pressure range of step (1) is 45 kPa-55 kPa.

5. The method for removing foaming gas from the inner packaging material for fruits in a space station according to claim 2, characterized in that: The pressure relief pressure in step (2) is 75-85 kPa.

6. The method for removing foaming gas from the inner packaging material for fruits in a space station according to claim 5, characterized in that: The pressure relief pressure in step (2) is 80 kPa.

7. The method for removing foaming gas from the inner packaging material for fruits in a space station according to claim 2, characterized in that: The temperature of the ventilation environment in step (3) is not less than 20°C.

8. The method for removing foaming gas from the inner packaging material for fruits in a space station according to claim 2, characterized in that: The step (3) of allowing the mixture to stand for 3 to 15 days.

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