An inflatable protective vacuum packaging bag and a manufacturing process thereof

Abstract

This invention discloses an inflatable protective vacuum packaging bag and its manufacturing process, belonging to the field of packaging bag technology. The packaging bag includes an outer bag body and an inner bag body. The outer bag body is formed by sealing an inner and outer film on all four sides, creating a sealed inflatable buffer cavity between the inner and outer films. The outer bag body is shaped like a "U" with an open top. The inner bag body is made of a single layer of heat-sealable plastic film, with the same shape as the outer bag body but smaller in size. The inner bag body is fitted inside the outer bag body, and the inner and outer bags are heat-sealed only at the edge of the top opening, forming a gap space between the outer surface of the inner bag body and the inner surface of the outer bag body. The outer bag body has ventilation holes penetrating the inner and outer films. The inner and outer films are heat-fused together at the hole walls, keeping the inflatable buffer cavity sealed at the perforation. The outer bag body also has a pressure-limiting and venting structure communicating with the inflatable buffer cavity. This structure closes when the air pressure inside the inflatable buffer cavity is below a preset threshold and opens to vent when it exceeds the preset threshold.

Description

Technical Field

[0001] This invention relates to the field of packaging bag technology, specifically to a double-layer protective vacuum packaging bag with inflation cushioning and pressure limiting and degassing functions, and its manufacturing process. Background Technology

[0002] In logistics transportation and product storage, for fragile, moisture-sensitive, or sterile products, vacuum packaging bags are typically used for inner sealing, followed by an outer protective bag to prevent damage to the inner bag due to impacts or compression during transport. The typical structure of existing double-layer packaging bags involves directly inserting the inner bag containing the product into the outer bag, and then sealing the outer bag. The drawbacks of this structure are: there is no fixed connection between the outer and inner bags, making them prone to relative sliding during transport, leading to reduced protective effectiveness; furthermore, the outer bag is usually a single-layer structure with limited impact and compression resistance.

[0003] To enhance protective performance, existing technologies have developed outer bag structures with inflatable cushioning chambers, such as a sealed chamber filled with gas between the inner and outer layers of the bag. However, such inflatable packaging bags face new problems in use: when subjected to abnormal compression, the air pressure inside the inflation chamber rises sharply, posing a risk of bag bursting. If a normally open vent is provided in the inflation chamber, the injected gas will continuously leak, making it impossible to maintain the cushioning thickness.

[0004] In addition, the following problems exist with the combined structure of inner bag vacuum packaging and outer bag inflation protection: when the inner bag is vacuumed and shrunk, if the air in the gap between the inner bag and the outer bag cannot be discharged in time, it will hinder the shrinkage and deformation of the inner bag, and may even cause the outer bag to be sucked in, affecting the protective effect.

[0005] Therefore, there is an urgent need for a packaging bag structure that can maintain the fullness of the inflation buffer chamber, automatically release pressure and prevent explosion under abnormal high pressure, and ensure smooth air release between the inner and outer bags when the inner bag is vacuumed. Summary of the Invention

[0006] 1. Technical problem to be solved: The purpose of this invention is to provide an inflatable protective vacuum packaging bag and its manufacturing process, so as to solve the problems of easy-to-explode bags, poor air exhaust during vacuuming of the inner bag, and unstable connection structure between the inner and outer bags in the prior art.

[0007] 2. Technical Solution: To solve the above problems, the present invention adopts the following technical solution.

[0008] An inflatable protective vacuum packaging bag, comprising: An outer bag body, the outer bag body includes an inner layer film and an outer layer film, the four peripheral edges of the inner layer film and the outer layer film are heat-sealed and connected, so as to form a sealed inflation buffer cavity between the inner layer film and the outer layer film, the top of the outer bag body has an opening, and the overall shape is "U" shaped; An inner bag body, made of a single-layer heat-sealable plastic film, the shape of the inner bag body is the same as the shape of the outer bag body and the external dimensions are smaller than the internal dimensions of the outer bag body; The inner bag body is sleeved inside the outer bag body, the opening edge at the top of the inner bag body and the opening edge at the top of the outer bag body are fixedly connected by heat sealing, so that the inner bag body and the outer bag body are only connected at the opening edge at the top, and a gap space surrounding the inner bag body is formed between the outer surface of the inner bag body and the inner surface of the inner layer film; At least one gap ventilation hole is opened on the outer bag body, the gap ventilation hole penetrates through the inner layer film and the outer layer film, and connects the gap space with the external atmosphere; at the pore wall of the gap ventilation hole, the inner layer film and the outer layer film are in a thermally melted and combined state, so that the inflation buffer cavity remains sealed at the perforation position of the gap ventilation hole; A pressure-limiting and air-relieving structure is further provided on the outer bag body, the pressure-limiting and air-relieving structure is connected to the inflation buffer cavity, and the pressure-limiting and air-relieving structure is configured to remain closed when the air pressure in the inflation buffer cavity is lower than a preset threshold value, and open to relieve air when the air pressure in the inflation buffer cavity exceeds the preset threshold value.

[0009] Further, the pressure-limiting and air-relieving structure is a one-way pressure-limiting valve, the one-way pressure-limiting valve has an opening pressure, and the opening pressure of the one-way pressure-limiting valve is equal to the preset threshold value. Using a one-way pressure-limiting valve can achieve precise control of the opening pressure, and can automatically reset and seal after air relief, ensuring that the inflation buffer cavity always remains sealed under normal conditions.

[0010] Further, the pressure-limiting and air-relieving structure is a plurality of pressure-limiting micropores opened on the outer layer film, the aperture of the pressure-limiting micropores is 0.05 mm - 0.2 mm, and the preset threshold value corresponds to the air pressure difference inside and outside the inflation buffer cavity when the gas permeability of the pressure-limiting micropores changes significantly. By controlling the micropore aperture and using the difference in the gas permeability of the micropores under different pressure differences, the effects of low-pressure pressure maintenance and overpressure air relief are achieved, and the structure is simple and the cost is low.

[0011] Further, the preset threshold value is a relative pressure of 0.2 atm to 0.5 atm, that is, an absolute pressure of 1.2 atm to 1.5 atm. This threshold range can ensure that the inflation buffer cavity does not leak air during normal transportation bumps, and can relieve pressure in time when subjected to dangerous squeezing.

[0012] Further, the number of the gap ventilation holes is multiple, and they are symmetrically distributed in the two side regions of the outer bag body. The multiple symmetrically arranged gap ventilation holes can enable the air in the gap space to be evenly discharged when the inner bag body is evacuated and shrunk, avoiding deformation caused by local air retention.

[0013] Further, the width of the inner bag body is 85% to 95% of the inner width of the outer bag body. This dimensional matching relationship can ensure that the inner bag body can be smoothly pushed into the inner part of the outer bag body in a drawer-like manner before loading items. At the same time, after the inner bag body is evacuated and shrunk, its shrinkage deformation will not squeeze the inflatable buffer cavity, ensuring that the buffering effect of the inflatable buffer cavity is not affected.

[0014] Further, the inner bag body is made of a multi-layer co-extruded nylon film with a thickness of 60μm to 120μm. The multi-layer co-extruded nylon film has excellent oxygen barrier performance and mechanical strength, and can meet the long-term sealing requirements of vacuum packaging.

[0015] Further, the outer bag body is provided with a tear line or a tear notch at the heat-sealed connection near the top opening edge. During use, the user can tear the outer bag body along the tear line or the tear notch to separate the inner and outer bags, facilitating the removal of the inner bag body.

[0016] A manufacturing process for an inflatable protective vacuum packaging bag includes the following steps: Step S1: Stack the inner layer film and the outer layer film, and perform hot pressing and sealing on their four sides to form an outer bag body with a sealed inflatable buffer cavity, and reserve an inflation port at a predetermined position in the inflatable buffer cavity; Cut out a top opening along the inner side of the top edge sealing line of the outer bag body, making the outer bag body in a "U" shape; Fold the single-layer heat-sealable plastic film in half, use the folded edge as the bag bottom, and perform hot pressing and sealing on the two side edges to form an inner bag body with a top opening and in a "U" shape, and the external dimensions of the inner bag body are smaller than the internal dimensions of the outer bag body; Step S2: Push the inner bag body into the inner part of the outer bag body from the top opening of the outer bag body, and align the top opening edge of the inner bag body with the top opening edge of the outer bag body; Step S3: In the state where the inflatable buffer cavity is not inflated, perform one-time hot pressing and sealing on the aligned opening edges of the outer bag body and the inner bag body to form a combined bag body that is only connected at the opening edge; Step S4: Process at least one gap ventilation hole at a predetermined position of the outer bag body. The gap ventilation hole penetrates through the inner layer film and the outer layer film, and during the processing, the inner layer film and the outer layer film at the perforation edge are heated and fused into one body, so that the inflatable buffer cavity remains airtight at the perforation; And process a pressure-limiting air-release structure at a predetermined position of the outer bag body; Step S5: Inflate the air buffer cavity with gas to a predetermined thickness through the reserved air inlet, and then seal the air inlet.

[0017] Furthermore, in step S3, the heat-sealing temperature is 120°C to 160°C, the pressure is 0.3MPa to 0.6MPa, and the heat seal strength between the top opening edge of the outer bag and the top opening edge of the inner bag is 3N / 15mm to 8N / 15mm. This heat seal strength range ensures that the inner and outer bags do not separate during transportation, while also allowing the user to peel the inner and outer bags apart with appropriate force when needed.

[0018] 3. Beneficial effects: Compared with the prior art, the technical solution provided by this invention has the following advantages: (1) The present invention designs the outer bag body as a double-layer structure with a sealed inflatable buffer cavity, and sets a pressure limiting and venting structure on the outer bag body that communicates with the inflatable buffer cavity, so that the packaging bag can rely on the inflatable buffer cavity to provide full buffer protection under normal conditions; when the internal air pressure of the inflatable buffer cavity exceeds the preset threshold due to accidental compression, the pressure limiting and venting structure automatically opens to vent and prevent the bag from bursting; after the air pressure drops after venting, the pressure limiting and venting structure closes again, and some gas is still retained in the inflatable buffer cavity to continue to provide basic buffer protection, thus realizing the synergistic effect of active inflation protection and passive pressure limiting explosion prevention.

[0019] (2) This invention creates a vent hole on the outer bag body that connects the space between the inner and outer bags to the outside. During processing, the inner and outer membranes at the perforation point are heated and fused together, thus forming a venting channel while automatically sealing the perforation edge of the inflation buffer cavity. This allows air in the gap space to escape smoothly when the inner bag body is vacuum-shrinked, avoiding the problem of air stagnation hindering the inner bag body's shrinkage or causing the outer bag body to collapse. At the same time, it ensures the airtightness of the inflation buffer cavity at the vent hole. Since the opening position of the vent hole is not limited by the inflation buffer cavity area, it can be flexibly set at any suitable position on the outer bag body, simplifying the production process.

[0020] (3) In this invention, the inner bag body and the outer bag body are heat-sealed only at the top opening edge, with no connection at other parts. The inner bag body is slidably fitted inside the outer bag body, forming a drawer-like assembly structure. This structure not only facilitates the mechanized insertion of the inner bag body during production, but also ensures the integrity of the inflation buffer cavity by preventing the inner bag body from shrinking under vacuum during use, as its shrinkage deformation is not constrained by the inner wall of the outer bag body after vacuuming.

[0021] (4) In the manufacturing process of the present invention, the inflation step of the inflation buffer cavity is arranged after the outer bag body and the inner bag body are heat-sealed together, which ensures that the inflation buffer cavity is in an uninflated state during the heat-sealing process, the heat-sealed surface is flat, and the connection strength is uniform and reliable; at the same time, the gap ventilation hole and the pressure limiting and venting structure are processed before inflation, the process sequence is reasonable, and it is convenient for industrial continuous production.

[0022] It should be noted that the structures not described in this invention are not related to the design points and improvement directions of this invention, and are the same as or can be implemented using existing technologies, so they will not be elaborated here. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural diagram of the inflatable protective vacuum packaging bag in Embodiment 1 of the present invention; Figure 2 This is an installation diagram of the pressure-limiting and venting structure in Embodiment 1 of the present invention when it is a one-way pressure-limiting valve; Figure 3 This is a schematic diagram of the pressure-limiting and venting structure in Embodiment 2 of the present invention when the pressure-limiting micropore is used; Figure 4 This is a cross-sectional exploded view of the outer bag and inner bag of the present invention.

[0024] Explanation of the labels in the diagram: 1. Outer bag body; 11. Inner membrane; 12. Outer membrane; 13. Inflatable buffer cavity; 2. Inner bag body; 3. Gap ventilation holes; 4. Gap space; 51. Pressure limiting micropores; 52. One-way pressure limiting valve. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] Example 1 (One-way pressure relief valve solution) Please see Figures 1 to 4 This embodiment provides an inflatable protective vacuum packaging bag, including an outer bag body 1 and an inner bag body 2.

[0027] The outer bag body 1 is composed of an inner layer film 11 and an outer layer film 12. Both the inner layer film 11 and the outer layer film 12 are made of PET / PE composite film, which has good heat-sealing performance and gas barrier performance. The inner layer film 11 and the outer layer film 12 have the same size. After laminating the two, the four sides are heat-sealed to form a structure with a closed perimeter. At this time, a sealed inflatable buffer cavity 13 is formed between the inner layer film 11 and the outer layer film 12. At about 10 mm inside the top-sealing line, a straight cut is made along the width direction to form the top opening of the outer bag body 1. The overall outer bag body 1 presents a "U" shape.

[0028] The inner bag body 2 is made of a seven-layer co-extruded nylon film with a thickness of 80 μm. Its oxygen transmission rate (ASTM D3985 standard, 23 °C, 0% RH) is 85 cm 3 / (m 2 ·d·atm). The co-extruded nylon film is folded in half, and the folded edge is used as the bottom of the bag. The two side edges are heat-sealed to form an inner bag body 2 with a top opening and also presenting a "U" shape. The width of the inner bag body 2 is 90% of the inner width of the outer bag body 1, and the length (height) is 95% of the inner length of the outer bag body 1, so that the inner bag body 2 can be smoothly pushed into the inner part of the outer bag body 1.

[0029] During production, the inner bag body 2 is pushed into the inner part of the outer bag body 1 from the top opening of the outer bag body 1, so that the top opening edge of the inner bag body 2 is aligned with the top opening edge of the outer bag body 1. At this time, a gap space 4 surrounding the inner bag body 2 is formed between the outer surface of the inner bag body 2 and the inner surface of the inner layer film 11 of the outer bag body 1.

[0030] As Figure 1 shown, three gap ventilation holes 3 with a pore diameter of 0.3 mm are formed by processing in the two side areas of the outer bag body 1. The gap ventilation holes 3 penetrate through the inner layer film 11 and the outer layer film 12. During the perforation process, the inner layer film 11 and the outer layer film 12 are melted and re-solidified at the pore wall, so that the inner layer film 11 and the outer layer film 12 are integrally hot-melted and combined at the perforation edge. Thus, the inflatable buffer cavity 13 remains sealed at the gap ventilation holes 3, and the gap ventilation holes 3 themselves constitute an independent channel connecting the gap space 4 and the outside atmosphere.

[0031] As an example processing method, an electrically heated conical tool heated to 200°C can be used to vertically puncture the inner membrane 11 and the outer membrane 12 on the outer bag body 1, forming three 0.3mm diameter vent holes 3. During the puncture process, the inner membrane 11 and the outer membrane 12 melt at the hole walls and solidify after the conical tool is removed, causing the inner membrane 11 and the outer membrane 12 to fuse together at the puncture edge, automatically forming a sealed hole wall. Alternatively, ultrasonic puncture or laser thermal puncture processes that can simultaneously fused and sealed the hole walls can be used. Thus, the inflation buffer cavity 13 remains sealed at the vent holes 3, while the vent holes 3 themselves constitute an independent channel connecting the gap space 4 to the outside atmosphere, ensuring that the airtightness of the inflation buffer cavity 13 is not compromised.

[0032] A one-way pressure relief valve 52 is installed on the upper part of the front of the outer bag body 1 (the surface of the outer membrane 12). The one-way pressure relief valve 52 is a commercially available miniature plastic one-way valve with a polyethylene valve body and a silicone valve core. Its opening pressure (relative pressure) is preset to 0.2 atm (i.e., it opens when the internal air pressure reaches approximately 1.2 atm). The air inlet of the one-way pressure relief valve 52 is connected to the inside of the inflation buffer chamber 13, and the air outlet faces the outside atmosphere. The installation method is as follows: a circular hole matching the air inlet of the one-way pressure relief valve 52 is made on the outer membrane 12, the air inlet of the one-way pressure relief valve 52 is passed through the circular hole, and the valve body is fixed to the outer membrane 12 by hot-melt welding.

[0033] An inflation port (not shown in the figure) is reserved on one side of the bottom of the outer bag 1. The inflation port is a small, unsealed opening for subsequent inflation into the inflation buffer chamber 13.

[0034] In the uninflated state, the aligned opening edges of the outer bag 1 and inner bag 2 are fed into a heat-sealing machine and heat-sealed in one go at a temperature of 140℃ and a pressure of 0.4MPa, forming a heat-sealed connection area with a width of 8mm. After heat sealing, the inner and outer bags are only connected at the top opening edge, with no connection at other parts. Testing showed that the heat seal strength of this connection is 5N / 15mm, which is within the peelable range.

[0035] Finally, air is injected into the inflation buffer chamber 13 through the reserved inflation port, causing the inflation buffer chamber 13 to expand to a thickness of about 10mm. Then, the inflation port is heat-sealed to complete the production of the packaging bag.

[0036] In use, the items to be packaged (such as medical devices, electronic components, etc.) are placed into the inner bag 2, and a vacuum is drawn inside the inner bag 2. After the vacuum level reaches -0.08MPa, the top opening of the inner bag 2 is heat-sealed. During the vacuuming process, the inner bag 2 gradually contracts, and the air in the gap space 4 is smoothly discharged through the vent holes 3 on both sides, without deformation of the outer bag 1. The inflation buffer chamber 13 remains full at all times, providing cushioning protection.

[0037] When the packaging bag is subjected to abnormal compression during transportation, the air pressure in the inflation buffer chamber 13 increases. Once the internal air pressure exceeds the opening pressure (1.2 atm) of the one-way pressure relief valve 52, the one-way pressure relief valve 52 automatically opens, slowly releasing some gas to reduce the pressure inside the chamber and prevent the bag from bursting. When the pressure drops back below the opening pressure, the one-way pressure relief valve 52 closes again, and approximately 80% of the gas remains in the inflation buffer chamber 13, continuing to provide basic cushioning protection.

[0038] When it is necessary to remove the item, the user can tear along the easy-tear line set at the heat-sealed connection at the top of the outer bag 1 to separate the inner and outer bags and remove the inner bag 2.

[0039] Example 2 (Pressure-limited microporous scheme) Please see Figure 3 The difference between this embodiment and embodiment 1 is that the pressure limiting and venting structure adopts multiple pressure limiting micropores 51 opened on the outer membrane 12, instead of using a one-way pressure limiting valve 52.

[0040] The processing method for the pressure-limiting micropores 51 is as follows: Micropores with a diameter of 0.1 mm ± 0.02 mm are formed on the surface area of ​​the outer membrane 12 corresponding to the inflation buffer chamber 13 using a laser drilling machine. The number of micropores is [number missing] per 10 cm [text missing]. 2 Set 5, evenly distributed.

[0041] In this embodiment, the outer membrane 12 has a thickness of 80 μm. By controlling the micropore size and pore density, the following effects can be achieved: When the relative air pressure inside the inflatable buffer chamber 13 is below 0.2 atm (i.e., the preset threshold), due to the small pressure difference, the gas molecules flow in the micropores in a molecular flow state, resulting in extremely low permeability. The pressure decay rate over 24 hours is less than 5%, which can be considered as a closed pressure-maintaining system. When the inflatable buffer chamber 13 is compressed, causing the internal relative air pressure to exceed 0.2 atm, the pressure difference increases, the gas flow enters a transitional flow state, the permeability increases significantly, and the gas slowly seeps out through the pressure-limiting micropores 51, achieving automatic pressure relief. After the pressure is relieved to below 0.2 atm, the permeability returns to a low level, and some gas is still retained in the inflatable buffer chamber 13 to maintain the basic buffer thickness.

[0042] The remaining structures, manufacturing processes, and usage methods of this embodiment are the same as those of Embodiment 1.

[0043] Example 3 (Detailed Manufacturing Process) The manufacturing process of the inflatable protective vacuum packaging bag of the present invention includes the following steps: Step S1: Pre-fabrication of the outer bag and the inner bag.

[0044] The inner film 11 and outer film 12 are unwound and stacked, then fed into a four-sided heat-sealing mold. They are heat-sealed for 2 seconds at a temperature of 150℃ and a pressure of 0.5MPa to form an outer bag 1 with a sealed air-filled buffer cavity 13. An air inlet of about 5cm is reserved on one side of the bottom. Subsequently, die-cutting is performed 10mm inside the top sealing line to cut out the top opening, making the outer bag 1 in the shape of a "U".

[0045] At the same time, the single-layer co-extruded nylon film is folded in half and fed into the bag making machine. Its two sides are hot-pressed and sealed to form an inner bag body 2 with an open top and a "U" shape. The outer width of the inner bag body 2 is controlled to be 90% of the inner width of the outer bag body 1, and the length is 95% of the inner length of the outer bag body 1.

[0046] Step S2: Fit the inner and outer bags together.

[0047] An automated bagging device pushes the inner bag 2 into the outer bag 1 through the top opening of the outer bag 1. The positioning mechanism ensures that the top opening edge of the inner bag 2 is aligned with the top opening edge of the outer bag 1.

[0048] Step S3: Heat seal the bag opening once.

[0049] With the inflation buffer chamber 13 uninflated, the assembled bag body is fed into the bag opening heat-sealing machine, and the aligned opening edges are heat-sealed. The heat-sealing parameters are: temperature 140℃, pressure 0.4MPa, and heat-sealing time 1.5 seconds. After heat sealing, a transverse heat-sealing line with a width of 8mm is formed. The inner and outer bag bodies are connected only at this heat-sealing line, with no connection at other parts. The heat seal strength is controlled at 5N / 15mm.

[0050] Step S4: Process the breathable structure and the pressure-limiting and venting structure.

[0051] The outer bag 1 is processed with a breathable structure and a pressure-limiting and venting structure. Three 0.3mm diameter gap vents 3 are formed on both sides of the outer bag 1. These gap vents 3 penetrate the inner membrane 11 and the outer membrane 12. During processing, the inner membrane 11 and the outer membrane 12 at the perforation edge are heated and fused together, thus forming a breathable channel while maintaining the airtightness of the inflation buffer chamber 13. Depending on the design, a one-way pressure-limiting valve 52 is installed at a predetermined position on the outer bag 1, or multiple 0.1mm diameter pressure-limiting micropores 51 are processed on the surface of the outer membrane 12 using a laser drilling machine.

[0052] Step S5: Inflate and seal.

[0053] Air is injected into the inflation buffer chamber 13 through the reserved inflation port until the inflation buffer chamber 13 expands to a thickness of 10mm. Inflation is then stopped, and the inflation port is immediately heat-sealed to complete the production of the packaging bag.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An inflatable protective vacuum packaging bag, characterized in that, Comprising: An outer bag body (1), the outer bag body (1) includes an inner layer film (11) and an outer layer film (12), the four peripheral edges of the inner layer film (11) and the outer layer film (12) are connected by heat sealing, so as to form a sealed inflation buffer cavity (13) between the inner layer film (11) and the outer layer film (12), the top of the outer bag body (1) has an opening, and the whole is in a "U" shape; An inner bag body (2), made of a single-layer heat-sealable plastic film, the shape of the inner bag body (2) is the same as the shape of the outer bag body (1) and the external dimensions are smaller than the internal dimensions of the outer bag body (1); The inner bag body (2) is sleeved inside the outer bag body (1), the opening edge of the top of the inner bag body (2) and the opening edge of the top of the outer bag body (1) are fixedly connected by heat sealing, so that the inner bag body (2) and the outer bag body (1) form a connection only at the opening edge of the top, and a gap space (4) surrounding the inner bag body (2) is formed between the outer surface of the inner bag body (2) and the inner surface of the inner layer film (11); At least one gap ventilation hole (3) is opened on the outer bag body (1), the gap ventilation hole (3) penetrates through the inner layer film (11) and the outer layer film (12), and connects the gap space (4) with the external atmosphere; at the pore wall of the gap ventilation hole (3), the inner layer film (11) and the outer layer film (12) are in a heat-melted combined state, so that the inflation buffer cavity (13) remains sealed at the perforation position of the gap ventilation hole (3); A pressure-limiting and air-relieving structure is further arranged on the outer bag body (1), the pressure-limiting and air-relieving structure is connected to the inflation buffer cavity (13), and the pressure-limiting and air-relieving structure is configured to remain closed when the air pressure in the inflation buffer cavity (13) is lower than a preset threshold value, and to open and relieve air when the air pressure in the inflation buffer cavity (13) exceeds the preset threshold value.

2. The inflatable protective vacuum packaging bag according to claim 1, characterized in that, The pressure-limiting and air-relieving structure is a one-way pressure-limiting valve (52), the one-way pressure-limiting valve (52) has an opening pressure, and the opening pressure of the one-way pressure-limiting valve (52) is equal to the preset threshold value.

3. The inflatable protective vacuum packaging bag according to claim 1, characterized in that, The pressure-limiting and air-relieving structure is a plurality of pressure-limiting micropores (51) opened on the outer layer film (12), the aperture of the pressure-limiting micropores (51) is 0.05 mm - 0.2 mm, and the preset threshold value corresponds to the air pressure difference inside and outside the inflation buffer cavity (13) when the gas permeability of the pressure-limiting micropores (51) changes significantly.

4. The inflatable protective vacuum packaging bag according to claim 2 or 3, characterized in that, The preset threshold value is a relative pressure of 0.2 atm to 0.5 atm, that is, an absolute pressure of 1.2 atm to 1.5 atm.

5. The inflatable protective vacuum packaging bag according to claim 1, characterized in that, The number of the gap ventilation holes (3) is multiple, and they are symmetrically distributed in the two side regions of the outer bag body (1).

6. The inflatable protective vacuum packaging bag according to claim 1, characterized in that, The width of the inner bag body (2) is 85% to 95% of the internal width of the outer bag body (1).

7. The inflatable protective vacuum packaging bag according to claim 1, characterized in that, The inner bag body (2) is made of a multi-layer co-extruded nylon film, and the thickness is 60 μm to 120 μm.

8. The inflatable protective vacuum packaging bag according to claim 1, characterized in that, The outer bag body (1) is provided with a tear line or a tear notch at the heat-sealing connection near its top opening edge.

9. A manufacturing process for an inflatable protective vacuum packaging bag as described in any one of claims 1 to 8, characterized in that, Including the following steps: Step S1: Overlap the inner film (11) and the outer film (12), and thermally press and seal the four sides thereof to form an outer bag body (1) with a sealed inflatable buffer cavity (13), and reserve an inflation port at a predetermined position of the inflatable buffer cavity (13); Cut out a top opening along the inner side of the top edge sealing line of the outer bag body (1) so that the outer bag body (1) is in a "U" shape; Fold the single-layer heat-sealable plastic film in half, use the folded edge as the bottom of the bag, and thermally press and seal the two side edges to form an inner bag body (2) with a top opening and in a "U" shape, and the external dimensions of the inner bag body (2) are smaller than the internal dimensions of the outer bag body (1); Step S2: Push the inner bag body (2) into the interior of the outer bag body (1) from the top opening of the outer bag body (1), and align the top opening edge of the inner bag body (2) with the top opening edge of the outer bag body (1); Step S3: In the state where the inflatable buffer cavity (13) is not inflated, thermally press and seal the aligned opening edges of the outer bag body (1) and the inner bag body (2) at one time to form a combined bag body connected only at the opening edge; Step S4: Process at least one gap ventilation hole (3) at a predetermined position of the outer bag body (1), the gap ventilation hole (3) penetrates through the inner film (11) and the outer film (12), and during the processing, the inner film (11) and the outer film (12) at the perforation edge are heated and fused together so that the inflatable buffer cavity (13) remains airtight at the perforation; and process a pressure-limiting and air-release structure at a predetermined position of the outer bag body (1); Step S5: Fill the inflatable buffer cavity (13) with gas to a predetermined thickness through the reserved inflation port, and then seal the inflation port.

10. The manufacturing process according to claim 9, characterized in that, In Step S3, the temperature of the thermal press sealing is 120 °C to 160 °C, the pressure is 0.3 MPa to 0.6 MPa, and the heat-sealing strength between the top opening edge of the outer bag body (1) and the top opening edge of the inner bag body (2) is 3 N / 15 mm to 8 N / 15 mm.

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