A PE cast embossed breathable membrane and its preparation method

Abstract

This application relates to the field of polymer materials, specifically disclosing a PE cast embossed breathable membrane and its preparation method. The PE cast embossed breathable membrane comprises the following components in parts by weight: 50-100 parts polyethylene, 7.5-15 parts POE, 35-70 parts inorganic filler, 15-30 parts thermally conductive material, 0.5-1.5 parts dispersant, 0.1-0.3 parts antioxidant, and 0.3-0.8 parts aluminum-zirconium coupling agent; the thermally conductive material comprises alumina and boron nitride fibers in a mass ratio of 1:0.8-1. The PE cast embossed breathable membrane of this application has the advantages of good air permeability, strong thermal conductivity, high tear resistance, and excellent mechanical strength.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, and more specifically, it relates to a PE cast embossed breathable membrane and its preparation method. Background Technology

[0002] Currently, PE cast embossed breathable membrane (hereinafter referred to as embossed breathable membrane) is widely used in the field of personal hygiene care products, especially in the fields of baby diapers, feminine hygiene napkins, adult hygiene protection products and breathable raincoats.

[0003] There are two main methods for manufacturing embossed breathable membranes: flat film casting and blown film casting. The former is the mainstream process used at home and abroad. It mainly involves filling the polyolefin with inorganic fillers, mainly calcium carbonate, to obtain a special material for the film. Then, the special material for the film is calendered and cast into a film. Finally, a unidirectional or bidirectional stretching action is applied to the film, which causes the polymer matrix to separate from the surface of the filler particles and develops interconnected microporous channels between the filler particles, thereby forming an embossed breathable membrane with micropores.

[0004] Embossed breathable films can be used not only in hygiene products such as baby diapers and sanitary napkins, but also in the manufacture of industrial, hospital, and military protective clothing. Polyolefin breathable films are seeing increased demand in the medical disposable protective clothing market. For breathable films used in protective clothing, while improving the breathability of the product, the thermal conductivity of the film is also an important indicator affecting its comfort. Regarding the related technologies mentioned above, the inventors discovered that current embossed breathable films used in the manufacture of protective clothing have poor thermal conductivity, resulting in a need to improve wearing comfort. Summary of the Invention

[0005] In order to improve the thermal conductivity of embossed breathable membranes and enhance the wearing comfort of protective clothing, this application provides a PE cast embossed breathable membrane and its preparation method.

[0006] In a first aspect, this application provides a PE cast embossed breathable membrane, which adopts the following technical solution:

[0007] A PE cast embossed breathable membrane comprises the following components in parts by weight: 50-100 parts polyethylene, 7.5-15 parts POE, 35-70 parts inorganic filler, 15-30 parts thermally conductive material, 0.5-1.5 parts dispersant, 0.1-0.3 parts antioxidant, and 0.3-0.8 parts aluminum-zirconium coupling agent;

[0008] The thermally conductive material comprises aluminum oxide and boron nitride fibers in a mass ratio of 1:0.8-1.

[0009] By adopting the above technical solution, polyethylene is used as the main material, which has good tensile strength, flexural ductility, and wear resistance. It can also be well compressed and sheared to form products. POE is used as a toughening agent, occupying a large space in the blend system, thus increasing the probability of cross-linking of the POE macromolecular chains, which improves the flexural strength and elongation at break of the material. Inorganic fillers in the polyethylene system tend to have uneven distribution due to their presence as particulate groups and aggregates. Therefore, an aluminum-zirconium coupling agent is added. The aluminum-zirconium coupling agent is a low-molecular-weight polymer containing zirconium aluminate, which complexes two organic ligands on its molecular backbone. One ligand imparts good hydroxyl stability and hydrolytic stability to the coupling agent, while the other ligand imparts good organic reactivity. Since the interfacial modification of inorganic fillers by the aluminum-zirconium coupling agent is irreversible, This not only improves the dispersibility of inorganic fillers and reduces system viscosity, but also enhances the bonding force between inorganic fillers and polyethylene due to the effect of functional groups. The addition of alumina and boron nitride fibers as thermally conductive fillers acts as nucleating agents during film stretching. During the thermal deformation of the polyethylene film during heating and stretching, the alumina and boron nitride fibers maintain their original shape, forming an elongated microporous structure around them. Furthermore, the close proximity of some micropores facilitates interpenetration, increasing the film's porosity and thus improving the permeability of water vapor and air. The high thermal conductivity of alumina and boron nitride fibers also enhances the film's heat dissipation, making the resulting breathable membrane less likely to cause stuffiness when used in protective clothing, thus improving wearing comfort.

[0010] Optionally, the polyethylene comprises LLDPE and mLLDPE in a mass ratio of 1:0.06-0.07.

[0011] By adopting the above technical solution, LLDPE, a low-density polyethylene, generally has a branched structure, thus exhibiting good extensibility and flexibility, as well as excellent resistance to environmental stress cracking, impact strength, and tear strength. It can be made into relatively thin and tear-resistant films. The added mLLDPE has a high relative molecular mass, regularly arranged molecular chains, a narrow relative molecular mass distribution, and uniformly distributed side chains in the main chain, with a certain amount of long-chain branching, resulting in superior tensile properties. This improves the tensile strength and elongation at break of LLDPE, giving protective clothing products strong tear resistance.

[0012] Optionally, the density of the LLDPE is 0.918-0.924 g / cm³. 3 The melt flow rate is 2-21 g / 10 min.

[0013] By adopting the above technical solutions, LLDPE with density and melt flow rate within the above range has the advantages of high elongation at break, good flexibility, and strong tear resistance.

[0014] Optionally, the density of the mLLDPE is 0.909-0.914 g / cm³. 3 The melt flow index is 1.5-2 g / 10 min.

[0015] By adopting the above technical solutions, the above mLLDPE has good tensile strength, high elongation at break, and strong tear resistance.

[0016] Optionally, the boron nitride fiber comprises the following raw materials in parts by weight: 0.5-1 parts hydroxy boron nitride, 3-6 parts polyvinyl alcohol, and 0.5-1 parts carbon nanotubes.

[0017] By adopting the above technical solutions, hydroxylated boron nitride possesses many excellent properties, such as high thermal conductivity and chemical stability. Carbon nanotubes have good mechanical properties, thermal conductivity, and thermal stability. When combined with polymer materials, they can improve the thermal properties of the matrix material. Polyoxyethylene has good chemical properties and thermal stability, good biocompatibility, and good spinnability. Its spinning process is stable and it has good fiber formation. Moreover, hydroxylated boron nitride can form hydrogen bonds with polyvinyl alcohol and is evenly dispersed in the polyvinyl alcohol spinning solution, forming a continuous thermally conductive network in the polyvinyl alcohol spinning solution. This greatly improves the mechanical properties and thermal conductivity of the composite material. Furthermore, the thermally conductive network formed by the interlocking of hydroxylated boron nitride and carbon nanotubes in the polyvinyl alcohol fiber matrix can also improve the air permeability of boron nitride fibers. Therefore, blending and spinning these three materials can yield boron nitride fibers with excellent mechanical properties, high thermal conductivity, and good air permeability.

[0018] Optionally, the method for manufacturing the boron nitride fiber includes the following steps:

[0019] Acidified carbon nanotubes are prepared by acidification treatment of carbon nanotubes.

[0020] Boron hydroxynitride was added to an aqueous solution of polyvinylpyrrolidone, stirred at 55-60℃ for 3-4 hours, cooled to room temperature, and filtered to obtain pretreated boron hydroxynitride.

[0021] Polyvinyl alcohol was dissolved in deionized water to prepare a solution with a concentration of 8-10 wt%. Pretreated boron nitride and acidified carbon nanotubes were added and stirred evenly to prepare a spinning solution. Boron nitride fibers were obtained by electrospinning.

[0022] By adopting the above technical solution, the aspect ratio and strong van der Waals forces of carbon nanotubes make them prone to aggregation, making it difficult to disperse and arrange in polymers, which greatly affects the thermal conductivity of composite materials. Therefore, the carbon nanotubes are first acidified to give them carboxyl and hydroxyl functional groups on their surface, thereby improving the dispersibility of carbon nanotubes in polyvinyl alcohol. Moreover, the carbon nanotubes with carboxyl groups form hydrogen bonds with the hydroxyl groups on the polyvinyl alcohol molecular chain, which can also improve the orientation of carbon nanotubes in polyvinyl alcohol, thereby making the carbon nanotubes oriented along the fiber. After pretreatment with polyvinylpyrrolidone, boron nitride with hydroxyl groups is tightly bound to it through hydrogen bonds, giving the surface of boron nitride with more polar groups, thereby further improving its compatibility with polyvinyl alcohol and further improving the mechanical strength of the spun fibers.

[0023] Optionally, the boron nitride fibers undergo the following pretreatment:

[0024] Tetrabutyl titanate and chitin were dissolved in anhydrous ethanol, mixed evenly, glacial acetic acid was added, stirred for 1-2 hours, and then vacuum dried to obtain titanium dioxide-chitin composite material.

[0025] Dissolve polyvinyl alcohol in deionized water, add the titanium dioxide-chitosan composite material, heat to 80-90℃, stir evenly, add borax, mix well, keep warm for 1-2 hours, add boron nitride fiber, freeze at -15~20℃ for 10-12 hours, and thaw at room temperature.

[0026] By adopting the above technical solution, tetrabutyl titanate forms titanium dioxide under the action of glacial acetic acid, which has excellent photocatalytic antibacterial effect. Therefore, a titanium dioxide-chitosan composite material with antibacterial effect is made. When it is mixed with an aqueous solution of polyvinyl alcohol, hydrogen bonds are formed between chitosan and polyvinyl alcohol to build a dense physical cross-linked network, which can effectively disperse stress and improve the mechanical strength of the composite material. Therefore, a composite gel with high mechanical strength can be formed on the surface of boron nitride fiber. Borax, as a cross-linking agent, has electrostatic interaction with chitosan, and the mechanical strength of the three-dimensional network structure formed is improved. When the film is made into protective clothing, and the protective clothing is torn and cracks are generated, the cracks on the surface of boron nitride fiber can be glued together because dynamic borate bonds are formed between hydroxyl groups and borate. When the two broken parts are separated, the dynamic borate bond breaks, and when the two parts re-contact, borate bonds are immediately formed. Therefore, the surface pretreatment of boron nitride fiber can improve the tear resistance of boron nitride surface and inhibit the propagation of surface cracks.

[0027] Optionally, the inorganic filler is selected from at least one of calcium carbonate, mica powder, and talc powder.

[0028] Optionally, the dispersant comprises oxidized polyethylene wax and isoamyl alcohol in a mass ratio of 1:0.8-1.

[0029] By adopting the above technical solution, the oxidized polyethylene wax molecular chain has carboxyl and hydroxyl groups. After being compounded with isoamyl alcohol, a certain amount of ester groups are added to its long chain molecules, which has a good lubricating effect and increases the fluidity of the composite material.

[0030] Secondly, this application provides a method for preparing a PE cast embossed breathable membrane, which adopts the following technical solution:

[0031] A method for preparing a PE cast embossed breathable membrane includes the following steps:

[0032] Inorganic filler, thermally conductive filler and aluminum zirconium coupling agent are mixed for 10-15 minutes, dispersant and antioxidant are added, and stirred for 5-10 minutes. Then POE and polyethylene are added, and the mixture is intensively mixed at 146-150℃ for 8-10 minutes. The mixture is then extruded, granulated, cast into a film, and embossed to obtain a PE cast embossed breathable film.

[0033] By adopting the above technical solution, inorganic fillers and thermally conductive fillers are first treated with aluminum-zirconium coupling agent and then mixed with other raw materials, which can improve the dispersion of inorganic fillers and thermally conductive fillers in the film and improve thermal conductivity and mechanical strength.

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

[0035] 1. Since this application uses alumina and boron nitride fibers as thermally conductive materials, it can improve the breathability of the PE cast embossed breathable membrane while also making the breathable membrane have a thermal conductivity, thereby dissipating heat and improving the wearing comfort of protective clothing made of the membrane.

[0036] 2. In this application, it is preferred to pretreat hydroxylated boron nitride with polyvinylpyrrolidone, acidify carbon nanotubes, and then mix them with polyvinyl alcohol solution for spinning. This can further improve the dispersibility of carbon nanotubes and hydroxylated boron nitride in polyvinyl alcohol solution, improve the structural stability of the thermally conductive network in the fiber, and enhance the thermal conductivity, mechanical strength, and air permeability.

[0037] 3. In this application, tetrabutyl titanate, chitin, polyvinyl alcohol and other raw materials are preferably used to pretreat boron nitride fibers. Chitin and polyvinyl alcohol form a network structure with high mechanical strength on the surface of boron nitride fibers, while tetrabutyl titanate is used to prepare titanium dioxide, which improves the antibacterial properties of boron nitride fibers. Detailed Implementation

[0038] Examples of boron nitride fiber preparation 1-5

[0039] Preparation Example 1: 1 kg of carbon nanotubes were placed in 10 kg of mixed acid (concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1), refluxed at 80 °C for 3 h, cooled to room temperature, allowed to stand for 24 h, the supernatant was removed, centrifuged for 10 min, washed with deionized water, and dried at 40 °C to obtain acidified carbon nanotubes.

[0040] 1 kg of boron hydroxynitride was added to 1 kg of a 1 wt% aqueous solution of polyvinylpyrrolidone, stirred at 60 °C for 3 h, cooled to room temperature, and filtered to obtain pretreated boron hydroxynitride. The boron hydroxynitride was selected from Ruixi Biotechnology, R-BN-0298. 6 kg of polyvinyl alcohol was dissolved in deionized water to obtain an 8 wt% solution. The pretreated boron hydroxynitride and acidified carbon nanotubes were added, stirred evenly, and a spinning solution was prepared. Electrospinning was performed to obtain boron nitride fibers. The spinning voltage was 15 kV, the spinning solution flow rate was 0.5 ml / l, and the receiving distance was 15 cm.

[0041] Preparation Example 2: 0.5 kg of carbon nanotubes were placed in 5 kg of mixed acid (concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1), refluxed at 80 °C for 3 h, cooled to room temperature, allowed to stand for 24 h, the supernatant was removed, centrifuged for 10 min, washed with deionized water, and dried at 40 °C to obtain acidified carbon nanotubes.

[0042] 0.5 kg of boron hydroxynitride was added to 0.5 kg of an aqueous solution of polyvinylpyrrolidone with a concentration of 1 wt%, stirred at 55 °C for 4 h, cooled to room temperature, and filtered to obtain pretreated boron hydroxynitride. The boron hydroxynitride was selected from Ruixi Biotechnology, R-BN-0298.

[0043] 3 kg of polyvinyl alcohol was dissolved in deionized water to prepare a 10 wt% solution. Pretreated boron nitride and acidified carbon nanotubes were added and stirred evenly to prepare a spinning solution. Electrospinning was then performed to produce boron nitride fibers. The spinning voltage was 15 kV, the spinning solution flow rate was 0.5 ml / l, and the receiving distance was 15 cm.

[0044] Preparation Example 3: The difference from Preparation Example 1 is that boron hydroxynitride was not treated with polyvinylpyrrolidone.

[0045] Preparation Example 4: The difference from Preparation Example 1 is that the carbon nanotubes were not acidified.

[0046] Preparation Example 5: The difference from Preparation Example 1 is that no carbon nanotubes were added.

[0047] Example

[0048] Example 1: A PE cast embossed breathable membrane, the raw material amounts are shown in Table 1. In Table 1, the thermally conductive filler includes alumina and boron nitride fibers in a 1:1 mass ratio. The boron nitride fibers are selected from Ruixi Biotechnology, model R-BN-0239. The inorganic filler is calcium carbonate. The dispersant includes oxidized polyethylene wax and isoamyl alcohol in a 1:1 mass ratio. The antioxidant is antioxidant 1010. The aluminum-zirconium coupling agent is model LD-139. The polyethylene includes LLDPE and mLLDPE in a 1:0.07 mass ratio. The LLDPE is selected from Formosa Plastics Group (Taiwan), and its density is 0.924 g / cm³. 3 The melt flow rate was 21 g / 10 min, and the mLLDPE was selected from Dow Chemical 5500G, with a density of 0.914 g / cm³. 3 The melt flow rate is 1.5 g / 10 min.

[0049] The preparation method of the above-mentioned PE cast embossed breathable membrane includes the following steps:

[0050] Inorganic filler, thermally conductive filler and aluminum zirconium coupling agent are mixed and stirred at 105℃ and 500r / min for 15min. Dispersant and antioxidant are added and stirred for 10min. Then POE and polyethylene are added and kneaded at 150℃ for 8min. The mixture is then extruded, granulated, cast into a film and embossed to obtain a PE cast embossed breathable film.

[0051] Table 1. Raw material consumption of PE cast embossed breathable membranes in Examples 1-3

[0052]

[0053]

[0054] Example 2: A PE cast embossed breathable membrane, the raw material amounts are shown in Table 1. In Table 1, the thermally conductive filler includes alumina and boron nitride fibers in a mass ratio of 1:0.8. The boron nitride fibers are selected from Ruixi Biotechnology, model R-BN-0239. The inorganic filler is calcium carbonate. The dispersant includes oxidized polyethylene wax and isoamyl alcohol in a mass ratio of 1:0.8. The antioxidant is antioxidant 1010. The aluminum-zirconium coupling agent is model LD-139. The polyethylene includes LLDPE and mLLDPE in a mass ratio of 1:0.06. The LLDPE is selected from Exxon 1002KW, with a density of 0.918 g / cm³. 3 The melt flow rate was 2 g / 10 min, and the mLLDPE was selected from Primavista SP1020 from Japan, with a density of 0.909 g / cm³. 3 The melt flow rate is 2 g / 10 min.

[0055] The preparation method of the above-mentioned PE cast embossed breathable membrane includes the following steps:

[0056] Inorganic filler, thermally conductive filler and aluminum zirconium coupling agent are mixed and stirred at 105℃ and 500r / min for 10min. Dispersant and antioxidant are added and stirred for 5min. Then POE and polyethylene are added and kneaded at 146℃ for 10min. The mixture is then extruded, granulated, cast into a film and embossed to obtain a PE cast embossed breathable film.

[0057] Example 3: A PE cast embossed breathable membrane, which differs from Example 1 in that the amount of raw materials used is shown in Table 1.

[0058] Example 4: A PE cast embossed breathable membrane, which differs from Example 1 in that mLLDPE is not added.

[0059] Example 5: A PE cast embossed breathable membrane, which differs from Example 1 in that an equal amount of EVA is used instead of mLLDPE.

[0060] Example 6: A PE cast embossed breathable membrane, which differs from Example 1 in that the boron nitride fiber is made from Preparation Example 1.

[0061] Example 7: A PE cast embossed breathable membrane, which differs from Example 1 in that the boron nitride fiber is made from Preparation Example 2.

[0062] Example 8: A PE cast embossed breathable membrane, which differs from Example 1 in that the boron nitride fiber is made from Preparation Example 3.

[0063] Example 9: A PE cast embossed breathable membrane, which differs from Example 1 in that the boron nitride fiber is made from Preparation Example 4.

[0064] Example 10: A PE cast embossed breathable membrane, differing from Example 1 in that the boron nitride fibers are prepared using Example 5.

[0065] Example 11: A PE cast embossed breathable membrane, which differs from Example 6 in that the boron nitride fiber is pretreated as follows: 25g tetrabutyl titanate and 20g chitin are dissolved in 80g anhydrous ethanol, mixed evenly, 25g glacial acetic acid is added, stirred for 1h, and vacuum dried to obtain titanium dioxide-chitin composite material.

[0066] Dissolve 100g of polyvinyl alcohol in 200g of deionized water, add 20g of titanium dioxide-chitosan composite material, heat to 90℃, stir evenly, add 10g of borax, mix well, keep warm for 2h, add 35g of boron nitride fiber, freeze at -20℃ for 10h, and thaw at room temperature.

[0067] Example 12: A PE cast embossed breathable membrane, differing from Example 6 in that the boron nitride fibers undergo the following pretreatment:

[0068] Dissolve 20g of chitin in 80g of anhydrous ethanol and mix well to obtain chitin material.

[0069] Dissolve 100g of polyvinyl alcohol in 100g of deionized water, add 20g of chitin material, heat to 90℃, stir evenly, add 10g of borax, mix well, keep warm for 2 hours, add 35g of boron nitride fiber, freeze at -20℃ for 10 hours, and thaw at room temperature.

[0070] Example 13: A PE cast embossed breathable membrane, differing from Example 6 in that the boron nitride fibers undergo the following pretreatment:

[0071] 25g tetrabutyl titanate and 20g chitin were dissolved in 80g anhydrous ethanol, mixed evenly, and then 25g glacial acetic acid was added. The mixture was stirred for 1 hour and then vacuum dried to obtain titanium dioxide-chitin composite material.

[0072] Add 20g of titanium dioxide-chitosan composite material to 200g of deionized water, heat to 90℃, stir evenly, keep warm for 2h, add 35g of boron nitride fiber, freeze at -20℃ for 10h, and thaw at room temperature.

[0073] Comparative Example

[0074] Comparative Example 1: A PE cast embossed breathable membrane, which differs from Example 1 in that it does not contain alumina.

[0075] Comparative Example 2: A PE cast embossed breathable membrane, which differs from Example 1 in that boron nitride fibers are not added.

[0076] Comparative Example 3: A microporous polyethylene membrane, using 30% by weight of ultra-high molecular weight polyethylene with an intrinsic viscosity of 800 ml / gm as component I, and 70% by weight of ultra-high molecular weight polyethylene with a kinematic viscosity of (7-8) mm at 100°C. 2 Paraffin oil of / s is used as component II. Using a casting method, according to the above preparation steps, firstly, polyethylene and filler are extruded using a twin-screw extruder and then enter the cooling roller area. The contact roller and cooling roller are adjusted to 22℃ to cool the mixed sheet after cooling. A pressure roller with a 1.5mm gap to the cooling roller presses the mixed sheet onto the cooling roller, allowing it to cool fully and form a sheet with a thickness of 900μm. Then, it is placed in a subsequent biaxial stretching machine for stretching to form a film. During stretching, the transverse and longitudinal stretching ratios are both greater than 3, with a total stretching ratio of 10. The filler is removed by solvent extraction with methyl ethyl ketone (MEK), and heat-set. Finally, a film with a thickness of 12μm is formed.

[0077] Performance testing

[0078] PE cast embossed breathable membranes were prepared according to the methods in the examples and comparative examples, and their various properties were tested according to the following methods. The test results are recorded in Table 2.

[0079] 1. Water vapor transmission rate: The test was conducted according to GB / T21529-2008 "Determination of water vapor transmission rate of plastic films and sheets - Electrolytic sensor method". The sample was a circular film with a diameter of 60 mm.

[0080] 2. Thermal conductivity: The test was conducted using a laser thermal conductivity meter. The thin film sample size was 10mm×10mm. Graphite was uniformly sprayed on the upper and lower surfaces of the sample. The test temperature was 25℃.

[0081] 3. Tensile strength: Tested in accordance with GB / T13022-1991 "Test Method for Tensile Properties of Plastic Films".

[0082] 4. Tear strength: Tested in accordance with GB / T16578.1-2008 "Determination of tear resistance of plastic films and sheets - Part 1: Pants tear test method".

[0083] 5. Antibacterial rate: Tested according to GB / T31402-2015 "Test Method for Antibacterial Properties of Plastic Surfaces", the test bacteria is Staphylococcus aureus.

[0084] Table 2 Performance Testing of PE Cast Embossed Breathable Membrane

[0085]

[0086] As can be seen from the data in Table 2, the breathable membranes prepared in Examples 1-3 have high tensile strength, high thermal conductivity, and good air permeability. In Example 4, mLLDPE was not added, and in Example 5, EVA was used to replace mLLDPE. Compared with Example 1, although the air permeability and thermal conductivity of the breathable membranes prepared in Examples 4 and 5 did not change much, their tensile strength and tear resistance decreased.

[0087] In Examples 6 and 7, boron nitride fibers prepared in Preparation Example 1 and Preparation Example 2 were used, respectively. As shown in Table 2, the breathable membrane exhibited enhanced air permeability, increased antibacterial ability and thermal conductivity, and improved tensile strength and tear resistance.

[0088] In Example 8, boron nitride fibers prepared in Preparation Example 3 were used. Compared with Preparation Example 1, the boron nitride hydroxyl nitride was not pretreated with polyvinylpyrrolidone. In Example 9, compared with Example 1, boron nitride fibers prepared in Preparation Example 4 were used. In Preparation Example 4, carbon nanotubes were not acidified. As shown in Table 2, the tensile strength and tear resistance of the breathable membranes prepared in Examples 8 and 9 decreased, while the other properties remained largely unchanged.

[0089] In Example 10, boron nitride fibers prepared in Preparation Example 5 were used, without the addition of carbon nanotubes. Compared with Example 1, the tensile strength and tear resistance of the resulting breathable membrane decreased, and the breathability and thermal conductivity were also reduced.

[0090] In Example 11, boron nitride fibers were pretreated using raw materials such as tetrabutyl titanate and polyvinyl alcohol. Compared with Example 6, the breathable membrane prepared in Example 11 showed significantly increased thermal conductivity and antibacterial rate, as well as improved tensile strength and tear resistance.

[0091] In Example 12, no tetrabutyl titanate was added during the pretreatment of boron nitride fibers, resulting in decreased thermal conductivity and antibacterial properties compared to Example 6. In Example 13, although tetrabutyl titanate was used, polyvinyl alcohol and boric acid were not added, leading to reduced tensile strength and tear strength compared to Example 6.

[0092] Compared with Example 1, Comparative Examples 1 and 2 did not contain alumina and boron nitride fibers, respectively. The breathable membranes prepared in Comparative Examples 1 and 2 had reduced air permeability, decreased thermal conductivity, and worse tensile strength.

[0093] Comparative Example 3 is a microporous polyethylene membrane prepared by existing technology. Although it has good air permeability, it has a low thermal conductivity, poor heat dissipation effect, and insufficient antibacterial properties.

[0094] 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 PE cast embossed breathable film characterized in that, The components include the following weight parts: 50-100 parts of polyethylene, 7.5-15 parts of POE, 35-70 parts of inorganic filler, 15-30 parts of heat-conducting material, 0.5-1.5 parts of dispersant, 0.1-0.3 parts of antioxidant, 0.3-0.8 parts of aluminum-zirconium coupling agent; The heat-conducting material includes aluminum oxide and boron nitride fiber in a mass ratio of 1:0.8-1; The boron nitride fiber includes the following raw materials in weight parts: 0.5-1 parts of hydroxyl boron nitride, 3-6 parts of polyvinyl alcohol, and 0.5-1 parts of carbon nanotube; The boron nitride fiber is prepared by the following steps: The carbon nanotube is subjected to acid treatment to obtain acidified carbon nanotube; The hydroxyl boron nitride is added to an aqueous solution of polyvinylpyrrolidone, stirred at 55-60°C for 3-4h, cooled to room temperature, filtered, and pretreated to obtain hydroxyl boron nitride; The polyvinyl alcohol is dissolved in deionized water to obtain a solution with a concentration of 8-10wt%, the pretreated hydroxyl boron nitride and acidified carbon nanotube are added and stirred uniformly to obtain a spinning solution, and the solution is electrospun to obtain boron nitride fiber.

2. The PE cast embossed breathable film according to claim 1, characterized in that: The polyethylene includes LLDPE and mLLDPE in a mass ratio of 1:0.06-0.

07.

3. The PE cast embossed breathable film according to claim 1, characterized in that, The boron nitride fiber is pretreated by the following steps: Titanium tetrabutoxide and chitin are dissolved in anhydrous ethanol, mixed uniformly, acetic acid is added, stirred for 1-2h, and vacuum dried to obtain titanium dioxide-chitin composite material; The polyvinyl alcohol is dissolved in deionized water, the titanium dioxide-chitin composite material is added, heated to 80-90°C, stirred uniformly, borax is added, mixed uniformly, and heated for 1-2h, and the boron nitride fiber is added, frozen at - (15-20) °C for 10-12h, and thawed at room temperature.

4. The PE cast embossed breathable film according to claim 1, characterized in that, The inorganic filler is selected from at least one of calcium carbonate, mica powder, and talc powder.

5. The PE cast embossed breathable film according to claim 1, characterized in that, The dispersant includes polyethylene oxide wax and isopentyl alcohol in a mass ratio of 1:0.8-1.

6. The method of making a PE cast embossed breathable film according to any of claims 1-5 characterized in that, The method includes the following steps: The inorganic filler, heat-conducting filler, and aluminum-zirconium coupling agent are mixed for 10-15min, the dispersant and antioxidant are added and stirred for 5-10min, the POE and polyethylene are added, and the mixture is milled at 146-150°C for 8-10min, extruded, granulated, cast into a film, and embossed to obtain a PE cast embossed breathable film.

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