A shielding ton bag inner bag and a method for manufacturing the same

Abstract

The application relates to the technical field of ton bag lining materials, and particularly discloses a shielding ton bag lining bag and a preparation method thereof. The shielding ton bag lining bag is made of a multilayer composite film with a structure of PET / light-shielding, air-permeable and moisture-permeable layer / PA / PE, and the light-shielding, air-permeable and moisture-permeable layer is made of raw materials in the following proportions by weight: resin 40-75 parts; heavy calcium carbonate 20-40 parts; color master batch 5-10 parts; dispersant 2-5 parts; antioxidant 0.2-0.4 parts; polyimide nanofiber 4-6 parts; porous diatomite 1-3 parts; the preparation method comprises the following steps: uniformly mixing the resin, the heavy calcium carbonate, the color master batch, the dispersant, the antioxidant, the polyimide nanofiber and the porous diatomite, extruding and granulating to obtain light-shielding, air-permeable and moisture-permeable layer material; then taking the light-shielding, air-permeable and moisture-permeable layer material, PET, PA and PE to perform four-layer co-extrusion blow molding to obtain a multilayer composite film, and then processing the bag. The shielding ton bag lining bag obtained by the application can have excellent and stable air permeability and moisture permeability under the influence of temperature change environment.

Description

Technical Field

[0001] This application relates to the field of ton bag lining materials technology, and more specifically, it relates to a shielded ton bag lining bag and its preparation method. Background Technology

[0002] BOOM (Liquid Unit Bag) is a flexible transport packaging container with advantages such as moisture-proof, dust-proof, radiation-resistant, and robust safety. It also possesses sufficient structural strength. Because BOOMs are easy to load, unload, and handle, their efficiency is significantly improved, leading to rapid development in recent years. BOOMs typically have an inner liner bag inside, which enhances their load-bearing capacity, ensuring the safety of goods during transportation or storage, and protecting them from external environmental contamination and damage, such as dust, moisture, and static electricity.

[0003] The inner liner of a ton bag is typically made of multiple co-extruded materials. Common materials include multi-layer composites such as PET / Al / PA / PE, PA / Al / PE, and PET / Al / PE. The aluminum foil layer offers excellent barrier properties, good light-blocking effect, and a moisture and air permeability of less than 0.05. These materials combine the advantages of different materials through a composite process, resulting in a soft feel and low cost, making the liner widely applicable. When ton bag liners are used for certain fresh foods, they require not only good light-blocking but also good moisture and air permeability to facilitate the dissipation of moisture inside the goods, reducing the risk of dampness and mold. This is especially important for goods susceptible to moisture and mold, such as agricultural products and food; good air permeability can extend shelf life and maintain product quality. Therefore, the Al in the multi-layer composite material is often replaced with a black breathable and moisture-permeable material. This not only provides good light-blocking but also improves the breathability and moisture permeability of the ton bag liner, thus meeting the requirements for use with the aforementioned fresh foods.

[0004] Regarding the aforementioned technologies, the inventors believe that the black breathable and moisture-permeable materials used are easily affected by environmental factors during application. In particular, when there are large temperature changes in the external environment, the structure of the black breathable and moisture-permeable materials will be greatly damaged, thereby affecting the stable performance of their breathability and moisture permeability.

[0005] Therefore, there is an urgent need to propose a solution to address the aforementioned technical problems. Summary of the Invention

[0006] In order to ensure that the air permeability and moisture permeability of the inner liner of a ton bag can be maintained relatively stably under the influence of temperature changes, this application provides a shielded inner liner of a ton bag and its preparation method.

[0007] In a first aspect, this application provides a shielding ton bag inner liner, which adopts the following technical solution:

[0008] A shielded ton bag liner is made of a multi-layer composite film with a structure of PET / light-shielding, breathable, and moisture-permeable layer / PA / PE, wherein the light-shielding, breathable, and moisture-permeable layer is made of raw materials comprising the following parts by weight:

[0009] 40-75 parts of resin;

[0010] 20-40 parts of heavy calcium carbonate;

[0011] 5-10 parts of color masterbatch;

[0012] 2-5 parts dispersant;

[0013] Antioxidant 0.2-0.4 parts;

[0014] 4-6 parts of polyimide nanofibers;

[0015] 1-3 parts porous diatomaceous earth.

[0016] By adopting the above technical solution, in the bag structure of the shielded ton bag liner, PET is the outermost layer, providing good rigidity, transparency, and barrier properties; the light-blocking, breathable, and moisture-permeable layer can provide good light-blocking effect and excellent breathability and moisture permeability; PA is used to enhance the strength, puncture resistance, and chemical stability of the multilayer composite film; PE, as the innermost layer, can provide good heat-sealing properties and flexibility; therefore, the shielded ton bag liner made from the multilayer composite film with the above structure can meet the usage requirements of fresh food and bring excellent application results.

[0017] Meanwhile, in the aforementioned light-shielding, breathable, and moisture-permeable layer, heavy calcium carbonate, in its raw materials, not only serves as a filler but also plays a crucial role in "pore formation." During the preparation of the light-shielding, breathable, and moisture-permeable layer, calcium carbonate particles separate at the junction with the plastic film matrix, forming uniform micropores. These micropores are key to achieving the breathable and moisture-permeable function of the light-shielding, breathable, and moisture-permeable layer. Meanwhile, the color masterbatch can bring about a superior light-shielding effect. The matrix of the light-shielding, breathable, and moisture-permeable layer is mainly formed through the interaction between the resin material, heavy calcium carbonate, and color masterbatch. To further ensure the stable air and moisture permeability of the inner liner of the ton bag under the influence of temperature changes, a combination of polyimide nanofibers and porous diatomaceous earth is used. The nano-surface effect and fiber entanglement of the polyimide nanofibers, along with the porous structure of the diatomaceous earth itself, create a cross-linked and interwoven structure, forming a dot network within the light-shielding, air-permeable, and moisture-permeable layer. Furthermore, the excellent temperature resistance of both polyimide nanofibers and porous diatomaceous earth helps to fix and protect the microporous structure of the light-shielding, air-permeable, and moisture-permeable layer. Thus, even with significant temperature variations in the external environment, the air and moisture permeability of the inner liner of the shielded ton bag remains highly stable, significantly improving the overall application effect.

[0018] Preferably, the weight ratio of the polyimide nanofibers to the porous diatomaceous earth is 2:1.

[0019] By adopting the above technical solution, when polyimide nanofibers and porous diatomaceous earth in the above weight ratio are used together, the compounding effect between them is excellent. The resulting dot network structure can provide better protection for the microporous structure of the light-shielding, breathable and moisture-permeable layer during temperature changes, thereby keeping the breathability and moisture permeability of the inner lining of the shielded ton bag relatively stable.

[0020] Preferably, the polyimide nanofibers have a diameter of 150-250 nm; the porous diatomaceous earth has a pore size of 1-2 μm and a particle size of 10-15 μm.

[0021] By adopting the above technical solution, when polyimide nanofibers of the above specifications and porous diatomaceous earth are used together, the compounding effect between them is excellent. The resulting dot network structure is distributed more evenly and densely in the light-shielding, breathable and moisture-permeable layer. When affected by temperature changes, it can effectively protect the microporous structure of the light-shielding, breathable and moisture-permeable layer and avoid significant damage to the structure of the light-shielding, breathable and moisture-permeable layer. This allows the inner liner of the ton bag to play a more stable role in breathability and moisture permeability during application.

[0022] Preferably, the raw material of the light-shielding, breathable, and moisture-permeable layer also contains 3-7 parts by weight of functional additives, which are composed of polytetrafluoroethylene and nano-thermal conductive fillers, and the weight ratio of polytetrafluoroethylene to nano-thermal conductive fillers is 1:(4-8).

[0023] By adopting the above technical solution, polytetrafluoroethylene (PTFE) can remain stable over extreme temperature ranges and possesses extremely strong chemical inertness and strength. In the light-shielding, breathable, and moisture-permeable layer, it can work in conjunction with the dot-network structure formed by polyimide nanofibers and porous diatomaceous earth, and the introduction of a membrane structure for reinforcement enhances the protection of the microporous structure within the layer. The nano-effect of the nano-thermal conductive filler and the polyimide nanofiber components allows them to adhere and bond together, forming thermal conductivity pathways within the light-shielding, breathable, and moisture-permeable layer, thereby effectively preventing internal combustion within the layer. The material undergoes drastic thermal changes, significantly reducing damage to the microporous structure in the light-shielding, breathable, and moisture-permeable layer when affected by temperature variations. When polytetrafluoroethylene (PTFE) and nano-thermal conductive fillers are used as functional additives, their combination with the dot-network structure formed by polyimide nanofibers and porous diatomaceous earth further enhances their synergy. This results in excellent thermal regulation and protection when there are large temperature variations in the external environment, allowing the light-shielding, breathable, and moisture-permeable layer to exhibit superior breathability and moisture permeability, ultimately significantly improving the application stability of the ton bag inner liner.

[0024] Preferably, the weight ratio of the polytetrafluoroethylene to the nano-thermal conductive filler is 1:6.

[0025] By adopting the above technical solution, when polytetrafluoroethylene and nano-thermal conductive filler are used in combination at the above weight ratio, the compounding effect between them is excellent. They can effectively play a role in film strengthening and thermal regulation on the dot network structure formed by polyimide nanofibers and porous diatomaceous earth, and form a better compatibility. When there are large temperature changes in the external environment, they can effectively protect the microporous structure in the light-shielding, breathable and moisture-permeable layer, thereby making the corresponding improvement effect brought by the functional additives more effective.

[0026] Preferably, the nano-thermal conductive filler is composed of boron nitride and silicon carbide in a weight ratio of (2-5):1.

[0027] By adopting the above technical solutions, boron nitride and silicon carbide have excellent thermal stability, high thermal conductivity, high insulation and good mechanical strength. The combined application of the two can not only combine with polyimide nanofibers to exert excellent thermal conductivity, but also improve the structural dimensional stability of the light-shielding, breathable and moisture-permeable layer. Therefore, after the application of functional additives, the stability of the light-shielding, breathable and moisture-permeable layer under the influence of temperature changes is better.

[0028] Preferably, the particle size of the nano-thermal conductive filler is 50-100 nm.

[0029] By adopting the above technical solution, the nano-thermal conductive filler with the above particle size has good compatibility with polyimide nanofibers when used. The formed thermal conductivity pathway can fully act on the dot network structure formed by polyimide nanofibers and porous diatomaceous earth, and is well matched with the film strengthening effect brought by polytetrafluoroethylene. In this way, the corresponding effect brought by the application of functional additives is better.

[0030] Preferably, the dispersant is one or a combination of several of the following: stearamide, hexenyl bis-stearamide, glyceryl monostearate, glyceryl tristearate, microcrystalline wax, barium stearate, zinc stearate, calcium stearate, ethylene-acrylic acid copolymer, and ethylene-vinyl acetate copolymer.

[0031] By adopting the above technical solutions, the dispersant can ensure that heavy calcium carbonate is uniformly dispersed in the resin material, avoiding agglomeration, thereby reducing the occurrence of macropores and improving the air permeability and moisture permeability of the light-proof, breathable, and moisture-permeable layer; at the same time, the dispersant can also improve the processing performance of the light-proof, breathable, and moisture-permeable layer, enabling the raw materials used to exert excellent effects, thus obtaining a high-quality light-proof, breathable, and moisture-permeable layer; and the above-mentioned types of dispersants are all suitable for the preparation of light-proof, breathable, and moisture-permeable layers and can exert the above-mentioned excellent effects.

[0032] Preferably, the antioxidant is one or a combination of several of di-tert-butylphenol, triphenyl phosphate, o-phenylenediamine, and catechol.

[0033] By adopting the above technical solutions, antioxidants can effectively inhibit or reduce the rate of thermal oxidation reaction of resin macromolecules and delay the thermal and oxygen degradation process of resin, thereby significantly improving the heat resistance of resin. This helps to maintain the stability and performance of the light-shielding, breathable and moisture-permeable layer in high-temperature environments. All of the above-mentioned antioxidants are suitable for the preparation of light-shielding, breathable and moisture-permeable layers and can exert the above-mentioned excellent effects.

[0034] Secondly, this application provides a method for preparing a shielded ton bag inner liner, which adopts the following technical solution:

[0035] A method for preparing a shielded ton bag inner liner includes the following steps:

[0036] (1) Prepare raw materials including resin, heavy calcium carbonate, masterbatch, dispersant, antioxidant, polyimide nanofiber and porous diatomaceous earth according to the formula;

[0037] (2) After mixing the resin material, heavy calcium carbonate, masterbatch, dispersant, antioxidant, polyimide nanofiber and porous diatomaceous earth in step (1) evenly, the mixture is extruded and granulated to obtain a light-shielding, breathable and moisture-permeable layer material.

[0038] (3) Take the light-shielding, breathable and moisture-permeable layer material obtained in step (2) and PET, PA and PE and perform four-layer co-extrusion blow molding to obtain a multi-layer composite film with the structure of PET / light-shielding, breathable and moisture-permeable layer / PA / PE. Then, after bag making, the inner liner of the shielded ton bag is obtained.

[0039] By adopting the above technical solution, the above preparation method is simple to operate. In the preparation process of the light-shielding, breathable and moisture-permeable layer material, the raw materials are processed in one pot, which can ensure that the interaction between the raw materials can be well played, and the overall performance is better. It can finally obtain a shielding ton bag liner with excellent and stable quality, and it is also suitable for large-scale industrial production.

[0040] In summary, this application has the following beneficial effects:

[0041] 1. This application combines polyimide nanofibers and porous diatomaceous earth, utilizing the nano-surface effect and fiber entanglement of polyimide nanofibers and the porous structure of porous diatomaceous earth itself to form a cross-linked and interwoven structure, thereby forming a dot network structure in the light-shielding, breathable and moisture-permeable layer. When the external ambient temperature undergoes a large temperature change, the microporous structure of the light-shielding, breathable and moisture-permeable layer can be fixed and protected, so that the final shielded ton bag liner can still exhibit stable and good breathability and moisture permeability.

[0042] 2. When polytetrafluoroethylene and nano-thermal conductive filler are used as functional additives in this application, the combination of the two can be further enhanced by the dot network structure formed by polyimide nanofibers and porous diatomaceous earth, resulting in excellent thermal regulation and protection. This significantly improves the application stability of the inner lining bag of the shielded ton bag when it is affected by large temperature changes. Detailed Implementation

[0043] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0044] Unless otherwise specified, all raw materials used in the embodiments and comparative examples of this application are commercially available.

[0045] The metallocene linear polyolefin resin was purchased from MVLDPE (metallocene) Pryman Japan SP0540.

[0046] Low-density polyethylene resin was purchased from Qatar Petrochemical LA0710;

[0047] Heavy calcium carbonate was purchased from Nanzhao County Wandu Micron Technology Co., Ltd., with a specification of 325 mesh.

[0048] The masterbatch was purchased from Jinan Dahua Plastics Processing Plant.

[0049] Example

[0050] Example 1

[0051] A shielded ton bag liner is made from a multi-layer composite film with a structure of PET / light-shielding, breathable, and moisture-permeable layer / PA / PE. The raw materials used to prepare the light-shielding, breathable, and moisture-permeable layer and their corresponding weights are shown in Table 1. The shielded ton bag liner is prepared through the following steps:

[0052] (1) Prepare raw materials including resin, heavy calcium carbonate, masterbatch, dispersant, antioxidant, polyimide nanofiber and porous diatomaceous earth according to the formula;

[0053] (2) After mixing the resin material, heavy calcium carbonate, masterbatch, dispersant, antioxidant, polyimide nanofiber and porous diatomaceous earth in step (1) evenly, the mixture is extruded and granulated to obtain a light-shielding, breathable and moisture-permeable layer material.

[0054] (3) Take the light-shielding, breathable and moisture-permeable layer material obtained in step (2) and PET, PA and PE and perform four-layer co-extrusion blow molding to obtain a multi-layer composite film with the structure of PET / light-shielding, breathable and moisture-permeable layer / PA / PE. Then, after bag making, the inner liner of the shielded ton bag is obtained.

[0055] Note: In the above operation, the resin material is composed of metallocene linear polyolefin resin and low-density polyethylene resin in a weight ratio of 3:2; the diameter of the polyimide nanofibers is 200nm; the pore size of the porous diatomaceous earth is 1.5μm and the particle size is 12.5μm; the dispersant is stearamide; and the antioxidant is di-tert-butylphenol.

[0056] Example 2-3

[0057] A shielded ton bag liner bag, which differs from Example 1 in that the raw materials used to prepare the light-blocking, breathable and moisture-permeable layer and their corresponding weights are shown in Table 1.

[0058] Table 1. Raw materials and their weight parts (kg / part) used in the preparation of the light-shielding, breathable, and moisture-permeable layers in Examples 1-3.

[0059] raw material Example 1 Example 2 Example 3 resin material 57.5 40 75 Heavy calcium carbonate 60 20 40 Masterbatch 7.5 5 10 dispersant 3.5 2 5 antioxidants 0.3 0.2 0.4 Polyimide nanofibers 5 4 6 Porous diatomaceous earth 2 1 3

[0060] Example 4

[0061] A shielded ton bag liner bag differs from Example 1 in that the total amount of polyimide nanofibers and porous diatomaceous earth remains unchanged, but the weight ratio of the two is adjusted to 2:1.

[0062] Example 5

[0063] A shielded ton bag liner bag, which differs from Example 1 in that the diameter of the polyimide nanofibers is 150 nm; the pore size of the porous diatomaceous earth is 1 μm and the particle size is 10 μm.

[0064] Example 6

[0065] A shielded ton bag liner bag, which differs from Example 1 in that the polyimide nanofibers have a diameter of 250 nm; the porous diatomaceous earth has a pore size of 2 μm and a particle size of 15 μm.

[0066] Example 7

[0067] A shielded ton bag liner bag, which differs from Example 1, is provided in that the raw material of the light-shielding, breathable and moisture-permeable layer is also provided with 5 parts by weight of functional additives. The functional additives are composed of polytetrafluoroethylene and nano thermally conductive fillers in a weight ratio of 1:6, and the functional additives are added together with other raw materials in step (2). The nano thermally conductive fillers are composed of boron nitride and silicon carbide in a weight ratio of 3.5:1, and the particle size of the nano thermally conductive fillers is 75nm.

[0068] Example 8

[0069] A shielding ton bag liner bag, which differs from Example 7 in that the functional additives are added in 3 parts by weight.

[0070] Example 9

[0071] A shielded ton bag liner bag, which differs from Example 7 in that the functional additives added are 7 parts by weight.

[0072] Example 10

[0073] A shielded ton bag liner bag, which differs from Example 7 in that the functional additives are composed of polytetrafluoroethylene and nano thermally conductive fillers in a weight ratio of 1:4.

[0074] Example 11

[0075] A shielded ton bag liner bag, which differs from Example 7 in that the functional additives are composed of polytetrafluoroethylene and nano thermally conductive fillers in a weight ratio of 1:8.

[0076] Example 12

[0077] A shielded ton bag liner bag, which differs from Example 7 in that the nano thermally conductive filler is composed of boron nitride and silicon carbide in a weight ratio of 2:1.

[0078] Example 13

[0079] A shielded ton bag liner bag, which differs from Example 7 in that the nano thermally conductive filler is composed of boron nitride and silicon carbide in a weight ratio of 5:1.

[0080] Example 14

[0081] A shielded ton bag liner bag, which differs from Example 7 in that the particle size of the nano thermally conductive filler is 50 nm.

[0082] Example 15

[0083] A shielded ton bag liner bag, which differs from Example 7 in that the particle size of the nano thermally conductive filler is 100 nm.

[0084] Example 16

[0085] A shielded ton bag liner bag, which differs from Example 7 in that the light-shielding, breathable and moisture-permeable layer does not use polytetrafluoroethylene in its raw material.

[0086] Example 17

[0087] A shielded ton bag liner bag, which differs from Example 7 in that the light-shielding, breathable and moisture-permeable layer does not use nano-thermal conductive fillers in its raw material.

[0088] Comparative Example

[0089] Comparative Example 1

[0090] A shielded ton bag liner bag, which differs from Example 1 in that the light-shielding, breathable and moisture-permeable layer does not use polyimide nanofibers in its raw material.

[0091] Comparative Example 2

[0092] A shielded ton bag liner bag, which differs from Example 1 in that porous diatomaceous earth is not used in the raw material of the light-shielding, breathable and moisture-permeable layer.

[0093] Comparative Example 3

[0094] A shielded ton bag liner bag, which differs from Example 1 in that the light-shielding, breathable and moisture-permeable layer does not use polyimide nanofibers and porous diatomaceous earth in its raw materials.

[0095] Comparative Example 4

[0096] A shielded ton bag liner bag, which differs from Example 7 in that the light-shielding, breathable and moisture-permeable layer does not use polyimide nanofibers and porous diatomaceous earth in its raw materials.

[0097] Performance testing test samples: The shielded ton bag liner obtained in Examples 1-17 was used as test sample 1-17, and the shielded ton bag liner obtained in Comparative Examples 1-4 was used as control sample 1-4; wherein, the size of the shielded ton bag liner is 1.2m×1.2m×1.5m, and the thickness of each layer of its structure PET / light-shielding, breathable and moisture-permeable layer / PA / PE is 12μm, 50μm, 25μm and 100μm respectively.

[0098] Test Method: For the inner lining of shielded ton bags, the air permeability (g / m³) was measured according to the relevant contents of ASTM D1434 "Determination of air permeability of plastic films and sheets by differential pressure method" and GB / T 10004-2008 "Test method for moisture and oxygen permeability of plastic films for food packaging". 2 ·24h) and moisture permeability (g / m 2 The initial values ​​A1 and B1 were obtained from the 24-hour test.

[0099] Then, the inner liner of the shielded ton bag was placed in a high and low temperature alternating test chamber. The initial temperature was 25℃. The temperature was first increased to 80℃ at 3℃ / min, then decreased to -10℃ at 1.5℃ / min, followed by an increase to 25℃ at 2℃ / min. This was recorded as one cycle, and the process was repeated for 20 cycles. The air permeability (g / m³) was then measured according to the above method. 2 ·24h) and moisture permeability (g / m 2 The final values ​​A2 and B2 were obtained from the 24-hour test.

[0100] Finally, the technology of reducing air permeability and reducing moisture permeability was carried out. The air permeability reduction rate (%) = (A1-A2) / A1, and the moisture permeability reduction rate (%) = (B1-B2) / B1. The larger the air permeability reduction rate and the moisture permeability reduction rate, the worse the stability of the inner liner of the shielded ton bag under the influence of temperature change environment.

[0101] Following the above method, after testing the test samples 1-17 and the control samples 1-4 in sequence, the experimental results are recorded in Table 2.

[0102] Table 2 Test results of test samples 1-17 and control samples 1-4

[0103]

[0104]

[0105] Combining Examples 1-3 and Comparative Examples 1-3 with Table 2, it can be seen that the combination of polyimide nanofibers and porous diatomaceous earth in the light-shielding, breathable, and moisture-permeable layer can significantly improve the stability of air permeability and moisture permeability in temperature-changing environments. The above experimental tests show that both the reduction rate of air permeability and the reduction rate of moisture permeability are significantly reduced. While using either polyimide nanofibers or porous diatomaceous earth alone can improve the stability of air permeability and moisture permeability compared to not using either, the improvement is limited, and the sum of the improvement effects of using either alone is far less than the superior effect of using them together. Therefore, the combination of polyimide nanofibers and porous diatomaceous earth can bring about a significant improvement effect of 1+1>2. Furthermore, combining Example 4 with Table 2, it can be seen that when the external ambient temperature undergoes a large range of temperature changes, a weight ratio of 2:1 for polyimide nanofibers to porous diatomaceous earth can maintain relatively stable and excellent air permeability and moisture permeability of the inner lining of the shielded ton bag.

[0106] As can be seen from Examples 1 and 7-11, and in conjunction with Table 2, when polytetrafluoroethylene (PTFE) and nano-thermal conductive fillers are used as functional additives in this application, the application stability of the shielded ton bag liner is significantly improved when subjected to large-scale temperature changes. The reduction rates of air permeability and moisture permeability obtained from the above tests are both significantly reduced. Furthermore, as can be seen from Examples 12-15 and Table 2, the nano-thermal conductive fillers, composed of boron nitride and silicon carbide in a weight ratio of (2-5):1, and with a particle size of 50-100 nm, enable the functional additives to exert excellent and stable effects. Finally, as can be seen from Examples 17-18 and Table 2, using PTFE or nano-thermal conductive fillers alone does not significantly improve air permeability and moisture permeability stability as much as the effect of combining the two. Combined with Comparative Examples 1 and 4 and Table 2, it can be seen that without the use of polyimide nanofibers and porous diatomaceous earth, the corresponding improvement effect brought by the functional additives will be greatly reduced. This indicates that the combination of polytetrafluoroethylene and nano-thermal conductive filler in the functional additives is inseparable from the combination of polyimide nanofibers and porous diatomaceous earth. It is a necessary condition to ensure that the stability of the light-shielding, breathable and moisture-permeable layer is significantly improved under temperature changes, thereby obtaining a shielding ton bag liner with better application quality.

[0107] 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 shielded ton bag inner liner, characterized in that, It is made from a multilayer composite film with a structure of PET / light-shielding, breathable, and moisture-permeable layer / PA / PE, wherein the light-shielding, breathable, and moisture-permeable layer comprises the following raw materials in parts by weight: 40-75 parts of resin; 20-40 parts of heavy calcium carbonate; 5-10 parts of color masterbatch; 2-5 parts dispersant; Antioxidant 0.2-0.4 parts; 4-6 parts of polyimide nanofibers; 1-3 parts porous diatomaceous earth.

2. The shielded ton bag liner according to claim 1, characterized in that: The weight ratio of the polyimide nanofibers to the porous diatomaceous earth is 2:

1.

3. The shielded ton bag liner according to claim 1, characterized in that: The polyimide nanofibers have a diameter of 150-250 nm, and the porous diatomaceous earth has a pore size of 1-2 μm and a particle size of 10-15 μm.

4. The shielded ton bag liner according to claim 1, characterized in that: The raw material of the light-shielding, breathable and moisture-permeable layer also contains 3-7 parts by weight of functional additives, which are composed of polytetrafluoroethylene and nano thermally conductive fillers, and the weight ratio of polytetrafluoroethylene to nano thermally conductive fillers is 1:(4-8).

5. The shielded ton bag liner according to claim 4, characterized in that: The weight ratio of the polytetrafluoroethylene to the nano-thermal conductive filler is 1:

6.

6. The shielded ton bag liner according to claim 4, characterized in that: The nano-thermal conductive filler is composed of boron nitride and silicon carbide in a weight ratio of (2-5):

1.

7. The shielded ton bag liner according to claim 4, characterized in that: The particle size of the nano-thermal conductive filler is 50-100 nm.

8. The shielded ton bag liner according to claim 1, characterized in that: The dispersant is one or a combination of several of the following: stearamide, hexenyl bis-stearamide, glyceryl monostearate, glyceryl tristearate, microcrystalline wax, barium stearate, zinc stearate, calcium stearate, ethylene-acrylic acid copolymer, and ethylene-vinyl acetate copolymer.

9. The shielded ton bag liner according to claim 1, characterized in that: The antioxidant is one or a combination of several of the following: di-tert-butylphenol, triphenyl phosphate, o-phenylenediamine, and catechol.

10. The method for preparing the inner liner of the shielded ton bag according to claim 1, characterized in that: Includes the following steps: (1) Prepare raw materials containing resin, heavy calcium carbonate, masterbatch, dispersant, antioxidant, polyimide nanofiber and porous diatomaceous earth according to the formula; (2) After mixing the resin material, heavy calcium carbonate, color masterbatch, dispersant, antioxidant, polyimide nanofiber and porous diatomaceous earth in step (1) evenly, the mixture is extruded and granulated to obtain a light-shielding, breathable and moisture-permeable layer material. (3) Take the light-shielding, breathable and moisture-permeable layer material obtained in step (2) and PET, PA and PE and perform four-layer co-extrusion blow molding to obtain a multi-layer composite film with the structure of PET / light-shielding, breathable and moisture-permeable layer / PA / PE. Then, after bag making, the inner liner of the shielded ton bag is obtained.

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