A valve-type packaging bag and its preparation method

Abstract

This application relates to the field of polyolefin materials, specifically disclosing a valve-sealed packaging bag and its preparation method; a valve-sealed packaging bag includes a bag body and a valve; the bag body includes a moisture-proof base layer, a fiber breathable layer, and a highly breathable polyethylene film; the valve includes a moisture-proof base layer, a fiber breathable layer, and a heat-sealing layer; the preparation method is as follows: prepare the bag body and the valve, heat-seal three included angles of the bag body, and then heat-seal the valve to the other included angle of the bag body to obtain the valve-sealed packaging bag; this allows excess gas inside the valve-sealed packaging bag to be easily discharged when filling materials; and after the materials are packaged in the valve-sealed packaging bag, when placed in a humid environment, the materials inside the valve-sealed packaging bag are not easily affected by moisture, thereby ensuring the quality and grade of the contents inside the valve-sealed packaging bag.

Description

Technical Field

[0001] This application relates to the field of polyolefin materials, and more specifically, to a valve-type packaging bag and a method for preparing the same. Background Technology

[0002] Valve bags, also known as bottom-sealed bags, are filled with material through a valve at the top or bottom. They are filled into cubes using specialized filling equipment and then stacked. They have the advantages of high packaging efficiency, convenient transportation, strong sturdiness, and low breakage rate. Valve bags can be used for packaging edible powders, chemical powders, fertilizers, synthetic materials, explosives, grains, salts, mineral powders, or granular solid materials.

[0003] In the prior art, Chinese patent application document with publication number CN111348317A discloses a method for manufacturing a low melting point valve bag. The low melting point valve bag includes a valve bag body and a valve port. The valve port includes an outer valve port and an inner valve port. The outer valve port is located on the top right side of the valve bag body, and the inner valve port is located in the valve bag body at a position corresponding to the outer valve port. Several air outlet holes are arranged on the valve port.

[0004] Therefore, in order to ensure the discharge of excess gas inside the valve bag, the low melting point valve bag prepared in the prior art has several vent holes on the valve port. However, the presence of several vent holes makes it easy for moisture from the humid environment to enter the valve bag. For materials such as carbon black, grain, and chemical powder packaged in the valve bag, the entry of moisture can easily affect the quality of the packaged materials. After carbon black gets damp, it is not only easy to affect the mechanical strength of the carbon black, but also easy to cause scaling and other problems. The same applies to grain powder and chemical powder. The entry of humid gas will affect the quality of grain powder and chemical powder. Summary of the Invention

[0005] In order to prepare a valve-sealed packaging bag that facilitates the discharge of excess gas inside the bag during material filling, and that prevents the material inside the bag from being affected by moisture when placed in a humid environment after packaging, thereby ensuring the quality of the contents, this application provides a valve-sealed packaging bag and its preparation method.

[0006] In a first aspect, this application provides a valve-sealed packaging bag, which adopts the following technical solution:

[0007] A valve-sealed packaging bag includes a bag body and a valve opening; the bag body includes a moisture-proof base layer, a fiber breathable layer, and a highly breathable polyethylene film; the valve opening includes a moisture-proof base layer, a fiber breathable layer, and a heat-sealing layer.

[0008] By adopting the above technical solution, when the valve bag is filled with material, the valve opening is blocked by the material. Therefore, the air permeability of the fiber breathable layer provides a channel for the gas to overflow during the filling process. The gas is gradually transferred through the highly breathable polyethylene film and fiber breathable layer on the bag body to the fiber breathable layer at the valve opening, thereby expelling the excess gas inside the valve bag. This allows the valve bag to quickly expel gas while filling, ensuring filling density while reducing gas retention. Combined with the good elastic cushioning effect of the breathable fiber layer, the valve bag is not prone to bursting when squeezed or impacted, thus ensuring the sealing effect of the valve bag.

[0009] After the valve bag is filled with material, the valve opening is first initially heat-sealed to bond the surfaces of the valve openings together, while the fiber breathable layer remains permeable. After the initial heat-sealing, the valve bag is squeezed to release air, further reducing gas retention. Then, a heat-pressing heat seal is performed at the original initial heat-sealed position of the valve opening. During the heat-sealing process, the heat-sealing layer gradually melts, and with the help of pressure, the heat-sealing layer bonds the fiber breathable layer between the moisture-proof base layer and the heat-sealing layer. The fiber breathable layer is blocked, thus sealing the valve opening and blocking the air passage. Since the valve bag only has one opening, sealing the valve opening completely seals the valve bag, ensuring that the valve bag containing the material is not easily affected by the external humid environment. At the same time, the moisture-proof base layer is the outermost layer, preventing moisture from entering the interior of the valve bag. This gives the valve bag good waterproof and moisture-proof properties after sealing, ensuring that the material inside the valve bag does not get damp, thereby guaranteeing the quality and performance of the material inside.

[0010] Preferably, the heat-sealing layer comprises the following raw materials in parts by weight: 55-70 parts EVA, 20-35 parts POE, 30-50 parts polyethylene, 1-5 parts compatibilizer, 1-2 parts antioxidant, and 1-2 parts lubricant.

[0011] By adopting the above technical solution, EVA, POE, polyethylene, and compatibilizer are combined and the raw material amount is limited, so that the heat-sealing layer not only has high mechanical strength but also good flexibility. It can buffer the impact force and is not easily scratched, thus preventing valve leakage. If the polyethylene content is low, the heat-sealing layer will not be strong enough and will be easily damaged by hard materials, affecting the sealing effect. If the polyethylene content is high, it will easily affect the heat-sealing adhesion and impact resistance of the heat-sealing layer.

[0012] Preferably, the fiber breathable layer is composed of polyacrylonitrile fiber, carbon fiber and hydrophobic bamboo fiber in a mass ratio of 1:1-2:1-2.

[0013] By adopting the above technical solution, polyacrylonitrile fiber, carbon fiber, and hydrophobic bamboo fiber are combined. The flexibility of polyacrylonitrile fiber and hydrophobic bamboo fiber facilitates deformation, while carbon fiber serves as a supporting structure, facilitating the formation of a network structure by polyacrylonitrile fiber, carbon fiber, and hydrophobic bamboo fiber, creating network pores. When the valve bag is filled with material, the material compresses the gas, causing the gas to gradually impact the flexible fiber. After impact, the flexible fiber deforms, providing a path for gas flow. The compressed gas can also overflow through the network structure pores, thereby removing excess gas inside the valve bag and minimizing the backflow of gas from the external environment into the valve bag, creating a near one-way permeability effect.

[0014] The combination of polyacrylonitrile fiber, hydrophobic bamboo fiber, carbon fiber, moisture-proof base layer, and heat-sealing layer further improves the mechanical strength of the valve bag, making it less likely to be damaged when packaging hard materials, thus affecting the packaging effect. In addition, the high-strength valve bag has a long service life and is less prone to leakage and cracking during transportation.

[0015] Preferably, the polyacrylonitrile fiber is composed of polyacrylonitrile fiber filaments, acrylic resin, and multi-pore filler in a mass ratio of 1:0.1-0.3:0.1-0.4.

[0016] By adopting the above technical solution, during the valve bag filling process, the flexibility of polyacrylonitrile fiber combined with the permeability of the multi-pore filler facilitates the discharge of excess gas from the valve bag, ensuring the sealing effect of the valve bag packaging.

[0017] When the valve bag is filled and the valve opening is heat-sealed, the cross-linking bonding effect of acrylic resin on polyacrylonitrile fibers with EVA and POE improves the adhesion between the polyacrylonitrile fibers and the heat-sealing layer. This allows the heat-sealing layer to seal the breathable fiber layer between the moisture-proof base layer and the heat-sealing layer during the heat-sealing process. After heat-sealing, the breathable fiber layer becomes airtight, and the cross-linking seals the pores of the multi-porous filler, making it less prone to moisture absorption and ensuring the quality of the material contained in the valve bag. Combined with the waterproof and moisture-proof properties of acrylic resin and EVA, the moisture-proof properties of the valve bag are further enhanced, preventing the material contained in the valve bag from being affected by moisture and ensuring its quality.

[0018] Preferably, the multi-pore filler is prepared by modifying multi-pore perlite with a silane coupling agent.

[0019] By employing the above technical solution, multi-porous perlite and silane coupling agent are combined. The hydrophobicity of the silane coupling agent gives the multi-porous perlite a better hydrophobic effect, making it less likely to absorb moisture from the external environment when the valve bag is filled with materials. This ensures both the heat-sealing effect and the quality of the materials inside the valve bag. Furthermore, the multi-porous filler can combine with the carboxyl groups in the acrylic resin on the surface of the polyacrylonitrile fiber, improving the adhesion stability of the multi-porous filler on the polyacrylonitrile fiber filament surface. The flexible winding of the polyacrylonitrile fiber filaments, combined with the pores of the multi-porous perlite, further ensures that gas can escape during material filling. Simultaneously, when heat-sealing the valve opening of the valve bag, it also improves the adhesion between the heat-sealing layer and the fiber permeable layer, thereby further improving the sealing effect and minimizing the entry of humid gases from the external environment into the valve bag, which could affect the quality of the materials.

[0020] Preferably, the carbon fiber is composed of carbon fiber filaments and TPU melt in a mass ratio of 1:0.1-0.2.

[0021] By adopting the above technical solution, carbon fiber filaments and TPU melt are combined. The amino groups in the TPU on the surface of the carbon fiber filaments combine with the carboxyl groups in the acrylic resin on the surface of the polyacrylonitrile fiber, as well as the EVA and POE in the heat-sealing layer. This not only improves the bonding effect of polyacrylonitrile fiber and carbon fiber after heat sealing, but also increases the bonding density of the heat-sealing layer and the fiber breathable layer. This ensures that the valve port is airtight and moisture-proof after heat sealing, so that even if the valve bag is placed in a humid environment, the humid gas will not easily affect the material contained inside the valve bag, thereby ensuring the quality of the material.

[0022] The combination of carbon fiber filaments and TPU melt, with the carbon fiber filaments having high strength but insufficient toughness, and TPU having a certain degree of toughness, combined with the flexibility of polyacrylonitrile fiber and hydrophobic bamboo fiber, can improve the impact resistance of the valve bag, thereby extending the service life of the valve bag.

[0023] Preferably, the hydrophobic bamboo fiber is prepared by loading water-white rosin resin melt onto bamboo fiber filaments after treatment with a silane coupling agent.

[0024] By adopting the above technical solution, bamboo fiber filaments, silane coupling agent, and water-white rosin resin melt are combined. The bamboo fiber filaments have the adsorption effect to facilitate the adsorption of silane coupling agent, and the hydrophobicity of silane coupling agent enhances the hydrophobic effect of bamboo fiber filaments, minimizing water absorption. Meanwhile, the water-white rosin resin on the surface of bamboo fiber filaments can improve the bonding effect between hydrophobic bamboo fiber and polyacrylonitrile fiber and carbon fiber. At the same time, by using water-white rosin resin in combination with EVA and POE in the heat-sealing layer, the bonding effect between hydrophobic bamboo fiber filaments and heat-sealing layer can be improved, so that the sealed valve bag has a better sealing effect and is not easily affected by the external humid environment.

[0025] Preferably, the moisture-proof base layer is a PE moisture-proof film.

[0026] By adopting the above technical solution, the PE moisture-proof film has good moisture-proof properties, preventing moisture from entering the valve bag from a humid environment.

[0027] Secondly, this application provides a method for preparing a valve-sealed packaging bag, which adopts the following technical solution:

[0028] A method for preparing a valved packaging bag includes the following steps: preparing a bag body and a valve opening; heat-sealing three included corners of the bag body; and heat-sealing the valve opening to another included corner of the bag body to obtain a valved packaging bag.

[0029] By adopting the above technical solution, the valve-sealed packaging bag is prepared. The material is filled at the valve opening, and the valve opening is heat-sealed at one end of the bag body. When the material is filled into the bag body, the valve opening is initially heat-sealed to make the valve opening adhere and bond. After squeezing out the air, the valve opening is heat-sealed by heat pressure. Under the action of pressure, the fiber breathable layer in the valve opening is completely sealed. The prepared valve bag is not easily affected by moisture in a humid environment, thus ensuring the quality of the contents inside the valve bag.

[0030] Preferably, the valve port is prepared by the following method:

[0031] S1. Spray EVA melt evenly onto the surface of the moisture-proof base layer, 20-50g per square meter of surface, and then spray polyacrylonitrile fiber, carbon fiber and hydrophobic bamboo fiber evenly to obtain a composite layer.

[0032] S2. EVA melt is evenly sprayed onto the surface of the heat-sealing layer, with 20-50g sprayed per square meter of surface. Then it is covered on the composite layer and dried. The polyacrylonitrile fiber, carbon fiber and hydrophobic bamboo fiber form a fiber breathable layer to obtain the finished product.

[0033] By adopting the above technical solution, the bonding of EVA ensures that the fiber breathable layer adheres stably to the surface of the moisture-proof base layer, and that the heat-sealing layer adheres stably to the surface of the composite layer. Furthermore, by limiting the amount of coating applied to the surface, the breathability of the fiber breathable layer is guaranteed, preventing the EVA melt from blocking the pores of the fiber breathable layer and affecting its breathability. This allows excess gas inside the valve bag to be easily discharged during material filling. After the valve bag is filled, the material inside is less susceptible to moisture damage in humid environments, thus ensuring the quality and stability of the contents of the valve bag.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. When filling the valve bag with materials, the breathable effect of the fiber breathable layer is used to provide a channel for gas to overflow during the filling process, ensuring filling density while reducing gas retention; after filling is completed, the fiber breathable layer is sealed, which seals the valve opening and blocks the breathable channel; this ensures that the contents of the valve bag are not damp, thus ensuring the quality and performance of the contents.

[0036] 2. The combination of polyacrylonitrile fiber, carbon fiber, and hydrophobic bamboo fiber forms a network structure, creating network pores that provide near one-way air permeability. Furthermore, its high strength ensures that the valve bag is not easily damaged when packaging rigid materials, thus maintaining the packaging effect. The high-strength valve bag also has a long service life and is less prone to leakage and cracking during transportation.

[0037] 3. The combination of polyacrylonitrile fiber filaments, acrylic resin, and multi-pore filler utilizes the flexibility of polyacrylonitrile fiber combined with the permeability of the multi-pore filler to facilitate the discharge of excess gas from the valve bag. When the valve bag is filled and the valve opening is heat-sealed, the cross-linking bonding effect of the acrylic resin on the polyacrylonitrile fiber with EVA and POE improves the adhesion between the polyacrylonitrile fiber and the heat-sealing layer. Furthermore, the cross-linking seals the pores of the multi-pore filler. Combined with the waterproof and moisture-proof properties of acrylic resin and EVA, the moisture-proof performance of the valve bag is further enhanced, making the material contained in the valve bag less susceptible to moisture, thus ensuring the quality and safety of the material. Detailed Implementation

[0038] The present application will be further described in detail below with reference to the embodiments.

[0039] Example of heat-sealing layer preparation

[0040] Preparation Example 1: The heat-sealing layer was prepared using the following method:

[0041] Weigh out 65 kg of EVA, 30 kg of POE, and 40 kg of polyethylene, mix them thoroughly, then add 3 kg of compatibilizer, 1.5 kg of antioxidant, and 1.5 kg of lubricant and mix thoroughly. The mixture is then extruded to obtain a heat-sealing layer. The polyethylene is linear low-density polyethylene, the compatibilizer is maleic anhydride-grafted polyethylene, the antioxidant is antioxidant 1024, and the lubricant is polyethylene wax. The thickness of the heat-sealing layer is 0.2 mm.

[0042] Preparation Example 2: The difference between this preparation example and Preparation Example 1 is that:

[0043] Weigh 55kg of EVA, 20kg of POE, and 30kg of polyethylene, mix them evenly, then add 1kg of compatibilizer, 1kg of antioxidant, and 1kg of lubricant and mix evenly. The mixture is then extruded to obtain a heat-sealing layer.

[0044] Preparation Example 3: The difference between this preparation example and Preparation Example 1 is that:

[0045] Weigh 70kg of EVA, 35kg of POE, and 50kg of polyethylene, mix them evenly, then add 5kg of compatibilizer, 2kg of antioxidant, and 2kg of lubricant and mix evenly. The mixture is then extruded to obtain a heat-sealing layer.

[0046] Example of preparation of polyacrylonitrile fiber

[0047] Preparation Example 4: Polyacrylonitrile fibers were prepared using the following method:

[0048] Acrylic resin is heated to 120°C and completely melted to obtain acrylic resin melt.

[0049] Weigh 1 kg of porous perlite and soak and disperse it in 10 kg of silane coupling agent. The porous perlite is passed through a 150-mesh sieve. The silane coupling agent is KH-570. Stir at 200 r / min for 30 min. Then take out the porous perlite and dry it to prepare a porous filler.

[0050] 0.2 kg of molten acrylic resin was uniformly sprayed onto the surface of 1 kg of polyacrylonitrile fiber, followed by uniform spraying of 0.2 kg of multi-pore filler. After drying and dispersion until the polyacrylonitrile fiber filaments did not stick together or agglomerate, the finished polyacrylonitrile fiber was obtained; the length of the polyacrylonitrile fiber filament was 1 mm.

[0051] Preparation Example 5: The difference between this preparation example and Preparation Example 4 is that:

[0052] 0.1 kg of molten acrylic resin is uniformly sprayed onto the surface of 1 kg of polyacrylonitrile fiber, followed by uniform spraying of 0.1 kg of multi-pore filler. After drying and dispersion until the polyacrylonitrile fiber filaments do not stick together or agglomerate, the finished polyacrylonitrile fiber is obtained.

[0053] Preparation Example 6: The difference between this preparation example and Preparation Example 4 is that:

[0054] 0.3 kg of molten acrylic resin was uniformly sprayed onto the surface of 1 kg of polyacrylonitrile fiber, followed by uniform spraying of 0.4 kg of multi-pore filler. After drying and dispersion until the polyacrylonitrile fiber filaments did not stick together or agglomerate, the finished polyacrylonitrile fiber was obtained.

[0055] Example of carbon fiber preparation

[0056] Preparation Example 7: Carbon fibers were prepared using the following method:

[0057] Weigh out TPU and heat it to 120℃ until it is completely melted to obtain TPU melt.

[0058] 0.16 kg of TPU melt was uniformly sprayed onto the surface of 1 kg of carbon fiber filaments. After drying and dispersion until the carbon fiber filaments no longer clump together, the finished carbon fiber was obtained; the length of the carbon fiber filaments was 0.5 mm.

[0059] Preparation Example 8: The difference between this preparation example and Preparation Example 7 is that:

[0060] 0.1 kg of TPU melt is uniformly sprayed onto the surface of 1 kg of carbon fiber filaments, and then dried and dispersed until the carbon fiber filaments do not stick together or agglomerate, thus obtaining the finished carbon fiber product.

[0061] Preparation Example 9: The difference between this preparation example and Preparation Example 7 is that:

[0062] 0.2 kg of TPU melt is uniformly sprayed onto the surface of 1 kg of carbon fiber filaments, and then dried and dispersed until the carbon fiber filaments do not stick together or agglomerate, thus obtaining the finished carbon fiber product.

[0063] Preparation example of hydrophobic bamboo fiber

[0064] The water-white rosin resin in the following raw materials was purchased from Shangrao Jiumu Chemical New Materials Co., Ltd.; other raw materials and equipment are commercially available.

[0065] Preparation Example 10: Hydrophobic bamboo fiber was prepared by the following method:

[0066] Weigh out water-white rosin resin and heat it to 120°C until it is completely softened and melted to obtain water-white rosin resin melt.

[0067] 1 kg of bamboo fiber filaments were soaked and dispersed in 10 kg of silane coupling agent. The bamboo fiber filaments were bamboo charcoal fiber filaments with a length of 1 mm. The silane coupling agent was KH-570. The mixture was stirred at 200 r / min for 30 min. Then the bamboo fiber filaments were taken out, dried, and evenly sprayed with 0.25 kg of water-white rosin resin melt. After drying and dispersion until the bamboo fiber filaments did not stick together or agglomerate, the finished hydrophobic bamboo fiber was obtained.

[0068] Example of bag preparation

[0069] Preparation Example 11: The bag body was prepared by the following method:

[0070] S1. EVA molten liquid is uniformly sprayed onto the surface of the moisture-proof base layer, with 100g sprayed per square meter of surface; then, the polyacrylonitrile fiber prepared in Preparation Example 4, the carbon fiber prepared in Preparation Example 7, and the hydrophobic bamboo fiber prepared in Preparation Example 10 are mixed evenly and then uniformly sprayed onto the surface of the EVA molten liquid on the moisture-proof base layer to obtain a composite layer; the moisture-proof base layer is a PE moisture-proof film with a thickness of 0.5mm; S2. EVA molten liquid is uniformly sprayed onto the surface of a high-permeability polyethylene film, with 50g sprayed per square meter of surface, and then covered onto the surface of the composite layer. After drying, the finished product is obtained; the fiber breathable layer formed between the high-permeability polyethylene film and the moisture-proof base layer has a thickness of 2mm.

[0071] Example of valve port preparation

[0072] Preparation Example 12: The valve port was prepared by the following method:

[0073] S1. EVA molten liquid is uniformly sprayed onto the surface of the moisture-proof base layer, with 40g sprayed per square meter of surface. Then, the polyacrylonitrile fiber prepared in Preparation Example 4, the carbon fiber prepared in Preparation Example 7, and the hydrophobic bamboo fiber prepared in Preparation Example 10 are mixed evenly and then uniformly sprayed onto the surface of the EVA molten liquid on the moisture-proof base layer to obtain a composite layer. The moisture-proof base layer is a PE moisture-proof film with a thickness of 0.5mm. S2. EVA molten liquid is uniformly sprayed onto the surface of the heat-sealing layer prepared in Preparation Example 1, with 40g sprayed per square meter of surface. Then, it is covered onto the surface of the composite layer and dried to obtain the finished product. The fiber breathable layer formed between the heat-sealing layer and the moisture-proof base layer has a thickness of 2mm.

[0074] Preparation Example 13: The difference between this preparation example and Preparation Example 12 is that:

[0075] S1. EVA molten liquid is uniformly sprayed onto the surface of the moisture-proof base layer, with 20g sprayed per square meter of surface; then the polyacrylonitrile fiber prepared in Preparation Example 5, the carbon fiber prepared in Preparation Example 8, and the hydrophobic bamboo fiber prepared in Preparation Example 11 are mixed evenly and then uniformly sprayed onto the surface of the EVA molten liquid on the moisture-proof base layer to obtain a composite layer.

[0076] S2. EVA melt is uniformly sprayed onto the surface of the heat-sealing layer prepared in Example 2, with 20g sprayed per square meter of surface. It is then covered onto the surface of the composite layer and dried to obtain the finished product. The thickness of the fiber breathable layer formed between the heat-sealing layer and the moisture-proof base layer is 2mm.

[0077] Preparation Example 14: The difference between this preparation example and Preparation Example 12 is that:

[0078] S1. EVA molten liquid is uniformly sprayed onto the surface of the moisture-proof base layer, with 50g sprayed per square meter of surface; then the polyacrylonitrile fiber prepared in Preparation Example 6, the carbon fiber prepared in Preparation Example 9, and the hydrophobic bamboo fiber prepared in Preparation Example 12 are mixed evenly and then uniformly sprayed onto the surface of the EVA molten liquid on the moisture-proof base layer to obtain a composite layer.

[0079] S2. EVA melt is uniformly sprayed onto the surface of the heat-sealing layer prepared in Preparation Example 3, with 50g sprayed per square meter of surface. It is then covered onto the surface of the composite layer and dried to obtain the finished product. The thickness of the fiber breathable layer formed between the heat-sealing layer and the moisture-proof base layer is 2mm.

[0080] Example

[0081] Example 1: A valve-type packaging bag:

[0082] The bag body prepared in Preparation Example 11 is aligned and heat-sealed with three included corners, and the remaining included corner is aligned and heat-sealed with the valve opening prepared in Preparation Example 12. This ensures that the fiber breathable layer on the bag body and the fiber breathable layer on the valve opening are connected, and that the valve opening is connected to the inside of the bag body. The end of the valve opening away from the bag body can correspond to the discharge port of the filling machine. The material output by the filling machine can enter the inside of the bag body through the valve opening and be contained in the bag body, thus obtaining a valve opening packaging bag.

[0083] Example 2: The difference between this example and Example 1 is that:

[0084] The valve port is the valve port prepared in Preparation Example 13.

[0085] Example 3: The difference between this example and Example 1 is that:

[0086] The valve port is the valve port prepared in Preparation Example 14.

[0087] Example 4: The difference between this example and Example 1 is that:

[0088] In the heat-sealing layer, POE is replaced with EVA of equal mass.

[0089] Example 5: The difference between this example and Example 1 is that:

[0090] In the heat-sealing layer, 90 kg of EVA and 15 kg of polyethylene are mixed and stirred evenly. Then, 3 kg of compatibilizer, 1.5 kg of antioxidant and 1.5 kg of lubricant are added and mixed evenly. The mixture is then extruded to obtain the heat-sealing layer.

[0091] Example 6: The difference between this example and Example 1 is that:

[0092] In the fiber breathable layer, polyacrylonitrile fiber and hydrophobic bamboo fiber are replaced with glass fiber of equal mass. The glass fiber is 1mm long alkali-free glass fiber chopped filaments.

[0093] Example 7: The difference between this example and Example 1 is that:

[0094] The polyacrylonitrile fiber in the fiber breathable layer is a commercially available polyacrylonitrile fiber filament, which has not been treated with acrylic resin and multi-pore filler. The carbon fiber is a commercially available carbon fiber filament, which has not been treated with TPU melt. The hydrophobic bamboo fiber is an ordinary bamboo charcoal fiber filament, which has not been treated with silane coupling agent and water-white rosin resin melt.

[0095] Example 8: The difference between this example and Example 1 is that:

[0096] In the preparation of polyacrylonitrile fibers, an equal mass of ethyl cellulose solution is used to replace acrylic resin. The ethyl cellulose solution is a 1% by mass ethyl cellulose ethanol solution with an ethanol mass fraction of 99%.

[0097] Example 9: The difference between this example and Example 1 is that:

[0098] No multi-pore filler was added during the preparation of polyacrylonitrile fibers.

[0099] Example 10: The difference between this example and Example 1 is that:

[0100] In the preparation of multi-pore fillers in polyacrylonitrile fibers, the multi-pore perlite was not treated with silane coupling agents.

[0101] Example 11: The difference between this example and Example 1 is that:

[0102] No TPU melt was added during the carbon fiber preparation process; the carbon fiber is ordinary commercially available carbon fiber.

[0103] Example 12: The difference between this example and Example 1 is that:

[0104] During the preparation of hydrophobic bamboo fiber, the surface of the bamboo fiber filaments is not treated with water-white rosin resin melt.

[0105] Example 13: The difference between this example and Example 1 is that:

[0106] The hydrophobic bamboo fiber filaments in the fiber breathable layer are replaced with bamboo fiber filaments of equal mass.

[0107] Example 14: The difference between this example and Example 1 is that:

[0108] During the valve preparation process, 150g of S1 and EVA melt is sprayed per square meter, and 150g of S2 and EVA melt is sprayed per square meter.

[0109] Comparative Example

[0110] Comparative Example 1: The difference between this comparative example and Example 1 is that:

[0111] No fiber breathable layer was added to the bag body and valve opening.

[0112] Performance testing

[0113] 1. Breathability test

[0114] Referring to Examples 1-3, 6, 9, 14 and Comparative Example 1, valve-sealed packaging bags were prepared. After filling with material, the valve openings were sealed, and the temperature was raised to 120°C and held for 5 seconds to achieve preliminary heat sealing. Then, the air was vented by pressing (the venting position and time were exactly the same in all examples and comparative examples). The temperature was then raised to 120°C and heat-sealed for 1 minute under a pressure of 1.5 MPa to obtain the packaged material. The packaged valve bags were then evacuated. The amount of gas evacuated was the amount of residual gas after loading the material. The total amount of gas contained in the valve bag was recorded as the total gas volume. The residual gas volume / total gas volume * 100% = residual gas rate.

[0115] Table 1 Performance Test Table

[0116] project Residual gas rate / % Example 1 2.4 Example 2 3.5 Example 3 2.1 Example 6 5.4 Example 9 4.8 Example 14 4.0 Comparative Example 1 8.6

[0117] 2. Mechanical strength testing

[0118] Finished valve-mouth packaging bags were prepared using the preparation methods of Examples 1-14 and Comparative Example 1, respectively. The tensile strength was tested according to GB / T1040.3-2006 at a speed of 500 mm / min, and the data were recorded.

[0119] 3. Moisture resistance test

[0120] Finished valve-mouth packaging bags were prepared using the preparation methods of Examples 1-14 and Comparative Example 1, respectively. Carbon black was packaged in the valve-mouth packaging bags. The carbon black was the material after drying, and it was recorded as the initial carbon black moisture content (initial carbon black moisture content < 0.04%. The drying conditions and drying time of the initial carbon black moisture content of Examples 1-14 and Comparative Example 1 were the same, that is, the initial carbon black moisture content of Examples 1-14 and Comparative Example 1 was the same).

[0121] After filling with carbon black, the valve port is attached, the temperature is raised to 120°C and held for 5 seconds to achieve preliminary heat sealing, and then the air is vented by pressing (the venting position and time are exactly the same in all embodiments and comparative examples), and then the temperature is raised to 120°C and heat-sealed for 1 minute under a pressure of 1.5MPa to obtain the packaged material.

[0122] The packaged material was placed at 30°C and 90% relative humidity for 1 day to simulate the storage of the packaged material in a humid environment. The moisture content of the carbon black was tested again and recorded as the moisture content of the hygroscopic carbon black. The moisture content difference = moisture content of hygroscopic carbon black - initial carbon black moisture content. The moisture content difference of Examples 1-5 and 7-13 was recorded.

[0123] Furthermore, the tensile strength of the valve packaging bag after the wet treatment was tested again, and the wet tensile strength of Examples 1-13 was recorded.

[0124] Table 2 Performance Test Table

[0125] project Tensile strength / MPa Moisture content difference / % Wet tensile strength / MPa Example 1 37.4 0.07 36.9 Example 2 36.8 0.11 36.1 Example 3 37.7 0.06 37.3 Example 4 37.0 0.08 36.4 Example 5 36.0 0.10 34.7 Example 6 37.8 / 37.2 Example 7 35.2 0.13 32.5 Example 8 36.7 0.09 35.9 Example 9 36.3 0.08 35.7 Example 10 36.9 0.11 36.0 Example 11 36.5 0.10 35.8 Example 12 36.4 0.11 35.7 Example 13 36.1 0.15 34.9 Example 14 37.5 / / Comparative Example 1 30.6 / /

[0126] As can be seen from Examples 1-3 and Tables 1 and 2, the valve bag prepared in this application has a low residual gas rate, indicating that it is easy to discharge excess gas inside the valve bag during the packaging process. In addition, it has high tensile strength, and even under humid conditions, the valve bag is not easily permeable to moisture and does not affect the moisture content of the packaged material inside. At the same time, after the valve bag is placed in a humid environment for a period of time, it still has good tensile strength, with a small difference in moisture content and a small difference between the initial tensile strength and the wet tensile strength. This indicates that the valve bag has a good sealing effect and can still ensure the quality of the material contained inside the valve bag in a humid environment.

[0127] Combining Examples 1 and 4-14 with Tables 1 and 2, it can be seen that in Example 4, when the heat-sealing layer is replaced with the same mass of EVA, the tensile strength of the valve bag prepared in Example 4 is lower than that in Example 1, and the difference between the initial tensile strength and the wet tensile strength is greater than the corresponding difference in Example 1. This indicates that the combination of EVA, POE, and polyethylene can improve the mechanical strength and waterproof and moisture-proof effect of the finished product.

[0128] In Example 5, the heat-sealing layer contained 90 kg of EVA and 15 kg of polyethylene, and no POE was added. Compared with Example 1, the valve bag prepared in Example 5 had a lower tensile strength than that in Example 1, a greater difference in moisture content, and a greater difference between the initial tensile strength and the wet tensile strength. This indicates that the EVA content was higher and the polyethylene content was lower, resulting in a decrease in tensile strength.

[0129] In Example 6, the polyacrylonitrile fiber and hydrophobic bamboo fiber were replaced with the same mass of glass fiber in the fiber breathable layer. Compared with Example 1, the valve bag prepared in Example 6 had a higher residual gas rate when packaging materials. This indicates that glass fiber lacks flexibility and easily affects gas flow. In contrast, polyacrylonitrile fiber and hydrophobic bamboo fiber, due to their flexibility, can easily combine with carbon fiber to form a porous network structure, thereby improving the breathability and facilitating the discharge of residual gas.

[0130] In Example 7, the fiber material in the fiber breathable layer was ordinary fiber filament without any other treatment. Compared with Example 1, the valve bag prepared in Example 7 had a lower tensile strength than that in Example 1, a greater difference in moisture content, and a greater difference between the initial tensile strength and the wet tensile strength. This indicates that surface treatment of the fiber filament can improve the adhesion and compatibility between the fiber breathable layer and the heat-sealing layer, thereby giving the valve bag a better waterproof and moisture-proof effect after packaging.

[0131] In Example 8, the acrylic resin was replaced with an equal mass of ethyl cellulose solution during the preparation of polyacrylonitrile fiber. Compared with Example 1, the tensile strength of the valve bag prepared in Example 8 was lower than that in Example 1, the difference in moisture content was greater than that in Example 1, and the difference between the initial tensile strength and the wet tensile strength was greater than the corresponding difference in Example 1. This indicates that although the ethyl cellulose solution also has viscosity and can bond multi-pore fillers, the compatibility between ethyl cellulose and the heat-sealing layer is poor, thus affecting the packaging and sealing effect of the valve bag.

[0132] In Example 9, no multi-pore filler was added during the preparation of polyacrylonitrile fiber. Compared with Example 1, the valve bag prepared in Example 9 had a lower tensile strength than that in Example 1, a greater difference in moisture content, and a greater difference between the initial tensile strength and the wet tensile strength. When packaging materials, the residual gas rate was greater than that in Example 1. This indicates that the multi-pore filler can promote gas flow and improve the mechanical strength of the valve bag.

[0133] In Example 10, during the preparation of the multi-porous filler in polyacrylonitrile fiber, the multi-porous perlite was not treated with a silane coupling agent. Compared with Example 1, the tensile strength of the valve bag prepared in Example 10 was lower than that in Example 1, the difference in moisture content was greater than that in Example 1, and the difference between the initial tensile strength and the wet tensile strength was greater than the corresponding difference in Example 1. This indicates that the multi-porous perlite was not treated to be hydrophobic and was prone to absorbing moisture, which affected the sealing effect of the valve bag. When the packaged material was stored in a humid environment, it was easy for the material to absorb moisture and affect the quality of the material.

[0134] In Example 11, no TPU melt was added during the carbon fiber preparation process. Compared with Example 1, the valve bag prepared in Example 11 had a lower tensile strength than that in Example 1, a greater difference in moisture content, and a greater difference between the initial tensile strength and the wet tensile strength. This indicates that the TPU melt can not only improve the bonding compatibility between carbon fiber filaments and polyacrylonitrile fibers and hydrophobic bamboo fibers, but also improve the bonding compatibility between carbon fiber and the heat-sealing layer, thereby improving the mechanical strength of the valve bag while also enhancing its waterproof and moisture-proof effects.

[0135] In Example 12, during the preparation of hydrophobic bamboo fiber, the surface of the bamboo fiber filaments was not treated with water-white rosin resin melt. Compared with Example 1, the tensile strength of the valve bag prepared in Example 12 was lower than that in Example 1, the difference in moisture content was greater than that in Example 1, and the difference between the initial tensile strength and the wet tensile strength was greater than the corresponding difference in Example 1. This indicates that water-white rosin resin melt can improve the bonding compatibility between hydrophobic bamboo fiber and carbon fiber and polyacrylonitrile fiber, and can also improve the bonding compatibility between hydrophobic bamboo fiber and heat-sealing layer, thereby improving the mechanical strength of the valve bag while improving the waterproof and moisture-proof effect.

[0136] In Example 13, the same mass of bamboo fiber filaments were used to replace the hydrophobic bamboo fiber filaments in the fiber breathable layer. Compared with Example 1, the tensile strength of the valve bag prepared in Example 13 was lower than that in Example 1, the difference in moisture content was greater than that in Example 1, and the difference between the initial tensile strength and the wet tensile strength was greater than the corresponding difference in Example 1. This indicates that the bamboo fiber, without hydrophobic treatment, is prone to absorbing moisture, and when stored in a humid environment, it can easily affect the quality of the material inside the valve bag.

[0137] In the valve preparation process of Example 14, 150g of EVA melt was sprayed per square meter for both S1 and S2. Compared with Example 1, the residual gas rate of the valve packaging bag prepared in Example 14 was greater than that in Example 1 when packaging materials. This indicates that the higher amount of EVA melt sprayed can easily affect the gas transfer to the fiber breathable layer, thereby affecting the overflow of gas inside the valve packaging bag. The larger amount of gas inside the valve packaging bag makes it more prone to bursting and affecting the sealing effect when subjected to compression and impact after packaging.

[0138] Based on Example 1 and Comparative Example 1, and in conjunction with Tables 1 and 2, it can be seen that no fiber breathable layer was added to the bag body and valve opening of Comparative Example 1. Compared with Example 1, the tensile strength of the valve opening packaging bag prepared in Comparative Example 1 is lower than that in Example 1, and the residual gas rate is higher than that in Example 1 when packaging materials. This indicates that the fiber breathable layer can not only improve the mechanical strength of the valve opening packaging bag, but also facilitate the discharge of excess gas when filling the valve opening packaging bag with materials, thus ensuring the sealing effect.

[0139] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A valve ported packaging bag characterized by, The valve port comprises a moisture-proof base layer, a fiber air-permeable layer and a heat-sealing layer; the fiber air-permeable layer is composed of polyacrylonitrile fiber, carbon fiber and hydrophobic bamboo fiber in a mass ratio of 1:1-2:1-2; the polyacrylonitrile fiber is composed of polyacrylonitrile fiber silk, acrylic resin and multi-aperture filler in a mass ratio of 1:0.1-0.3:0.1-0.4; the multi-aperture filler is prepared by modifying multi-aperture perlite with a silane coupling agent.

2. A valve bag according to claim 1, wherein: The heat-sealing layer comprises the following raw materials in parts by weight: EVA 55-70 parts, POE 20-35 parts, polyethylene 30-50 parts, a compatibilizer 1-5 parts, an antioxidant 1-2 parts and a lubricant 1-2 parts.

3. A valve bag according to claim 1, wherein The carbon fiber is composed of carbon fiber silk and TPU melt in a mass ratio of 1:0.1-0.

2.

4. The valve-ported packaging bag of claim 1, wherein The hydrophobic bamboo fiber is prepared by loading water-white turpentine resin melt on bamboo fiber silk after treatment with a silane coupling agent.

5. A valve bag according to claim 1, wherein The moisture-proof base layer is a PE moisture-proof film.

6. A method of making a valve bag according to any one of claims 1-5, characterized in that, The method comprises the following steps: The bag body and the valve port are prepared, the bag body is heat-sealed at three angles, the valve port is heat-sealed with the bag body at another angle, and a valve port packaging bag is prepared.

7. A method of making a valve bag according to claim 6, wherein, The valve port is prepared by the following method: S1, evenly spraying EVA melt on the surface of the moisture-proof base layer, 20-50 g per square meter of surface, and then evenly spraying polyacrylonitrile fiber, carbon fiber and hydrophobic bamboo fiber to prepare a composite layer; S2, evenly spraying EVA melt on the surface of the heat-sealing layer, 20-50 g per square meter of surface, and then covering on the composite layer, drying treatment, polyacrylonitrile fiber, carbon fiber and hydrophobic bamboo fiber forming a fiber air-permeable layer, and preparing a finished product.