High-barrier infusion film and method for preparing the same

Abstract

The application relates to the technical field of packaging materials, and particularly discloses a high-barrier film for infusion and a preparation method thereof, which comprises an outer surface layer, an inner surface layer and a core layer, the core layer is composed of layer material A and layer material B which are alternately stacked, the layer material A comprises binary copolymerized polypropylene, the layer material B comprises styrene block copolymer, styrene block copolymer grafted maleic anhydride and a composite filler, the composite filler comprises modified kaolin and modified montmorillonite, the modified kaolin is kaolin modified by a phenyl silane coupling agent and nano silicon dioxide, and the modified montmorillonite is montmorillonite modified by hexadecyl trimethyl ammonium bromide and gamma-aminopropyl triethyl silane. The application realizes excellent high-barrier property and mechanical property of the film material by cooperating the multi-element modified inorganic filler with the layered structure.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, and specifically discloses a high-barrier infusion membrane and its preparation method. Background Technology

[0002] Currently, the materials used for large-volume parenteral bags in China are generally three-layer or five-layer co-extruded infusion membranes. The basic requirements for infusion membranes include: good flexibility, transparency, heat resistance, safety, mechanical strength, gas barrier properties, and processability.

[0003] The materials used in three-layer co-extruded infusion membranes are mainly polypropylene and styrene block copolymers. They offer advantages such as high hygiene and safety, low cost, and no need for cross-linking technology, gradually becoming the mainstream membrane for large-volume infusion bags. While three-layer co-extruded infusion membranes can meet the requirements of general large-volume infusion bag products, their use is often limited for some infusion products with high gas barrier requirements. For example, small-volume products of 50mL and below require high water vapor barrier properties, and amino acids require high oxygen barrier properties.

[0004] To improve the gas barrier properties of infusion membranes, traditional methods include adding barrier resins or inorganic fillers with good gas barrier properties to the membrane material. Barrier resins include two categories: polar resins such as EVOH and PA, and non-polar resins such as cyclic olefin polymers. EVOH or PA has good barrier properties against gases such as oxygen and carbon dioxide, but the monomers or oligomers of these materials are polar substances and easily dissolve into aqueous solutions, thus affecting drug compatibility. Furthermore, these polar barrier materials have poor water vapor barrier properties and cannot improve the water vapor barrier properties of the membrane material. Cyclic olefin polymers, as non-polar barrier materials, have good water vapor barrier properties, but they are more expensive and have higher material hardness, which significantly affects the flexibility of the infusion membrane. Inorganic fillers, especially two-dimensional inorganic fillers with high aspect ratio (such as kaolin), have high gas barrier properties against oxygen, carbon dioxide, and water vapor. However, when directly added to polymers, they have limited effect on improving the barrier properties of the membrane material due to poor compatibility between inorganic fillers and polymers, easy agglomeration, and irregular arrangement. They can also easily affect the transparency and mechanical properties of the membrane material.

[0005] While existing technologies have attempted to utilize single modified inorganic fillers or simple composite inorganic fillers, single modified inorganic fillers can only provide a one-dimensional barrier effect, and simple composite inorganic fillers are merely physical mixtures with weak interfacial bonding, failing to form a complementary and synergistic barrier system. Therefore, both methods offer limited improvements in the barrier performance of the membrane material, making it difficult to overcome existing technological bottlenecks. Consequently, developing an infusion membrane that achieves a synergistic effect of high barrier properties and excellent overall performance has become a pressing technical problem in this field. Summary of the Invention

[0006] This invention provides a high-barrier infusion membrane, which achieves excellent high barrier properties and mechanical properties through the combination of multi-component modified inorganic fillers and a layered structure.

[0007] This invention is achieved through the following technical solution:

[0008] On one hand, the present invention provides a high-barrier infusion membrane, comprising an outer surface layer, an inner surface layer and a core layer, wherein the core layer is composed of alternating layers of layer material A and layer material B; The layer material A comprises binary copolymer polypropylene; The layer material B includes styrene block copolymer, styrene block copolymer grafted maleic anhydride and composite filler, wherein the composite filler includes modified kaolin and modified montmorillonite; The modified kaolin is kaolin modified with phenylsilane coupling agent and nano-silica; The modified montmorillonite is montmorillonite modified with hexadecyltrimethylammonium bromide and γ-aminopropyltriethylsilane.

[0009] Specifically, the preparation method of modified kaolin is as follows: 5% of the total mass of kaolin and nano silica is dissolved in anhydrous ethanol, 0.5-2% of the mass of kaolin is added to nano silica, and then kaolin is added. After stirring for 10-20 minutes, the mixture is filtered and thoroughly dried to remove the anhydrous ethanol, thus obtaining modified kaolin.

[0010] The modified montmorillonite was prepared as follows: montmorillonite was added to deionized water and ultrasonically dispersed for 30-60 min to obtain a montmorillonite suspension with a mass fraction of 2-5%; hexadecyltrimethylammonium bromide was added to the suspension at a molar ratio of 1:1 to the cation exchange capacity of montmorillonite, and stirred at 70-80℃ for 2-4 h; then γ-aminopropyltriethoxysilane (5-10% of the mass of montmorillonite) was added, and stirring was continued for 3-5 h; after cooling, the mixture was filtered and washed until no bromide ions were present, and then dried to obtain the modified montmorillonite. The cation exchange capacity of montmorillonite was 80-120 mmol / 100g.

[0011] The preparation method of styrene block copolymer grafted with maleic anhydride is as follows: after uniformly mixing styrene block copolymer, maleic anhydride monomer and initiator (diisopropylbenzene peroxide), reaction extrusion is carried out to obtain styrene block copolymer grafted with maleic anhydride. The mass ratio of styrene block copolymer, maleic anhydride and initiator is 100:3.5:0.5.

[0012] In this invention, the mass ratio of the styrene block copolymer, the styrene block copolymer grafted with maleic anhydride, and the composite filler is 75-90:5-20:0.5-8, and the mass ratio of modified kaolin and modified montmorillonite in the composite filler is 3-5:1.

[0013] In this invention, the nano-silica has a particle size of 5-20 nm and a loading of 0.5-2%, and the modified montmorillonite has an interlayer spacing of 2-3.5 nm.

[0014] In this invention, the modified kaolin has an average flake diameter D1 of 1-3 μm and an aspect ratio of 50-100; the modified montmorillonite has an average flake diameter D2 of 0.1-1 μm and an aspect ratio of 100-1000; the single-layer thickness d_B of the layer material B is 2-10 μm, wherein 1 <d_B / D1<5,5<d_B / D2<25。

[0015] In this invention, the thickness ratio of layer material A to layer material B is 35-65:35-65, and the number of alternating layers is 2. n , where n is 4-6.

[0016] In this invention, the thickness of the high-barrier infusion membrane is 150-250 μm, and the thickness ratio of the inner surface layer, the core layer and the outer surface layer is 15-30:45-70:10-25.

[0017] In this invention, the outer layer comprises homopolymer polypropylene and styrene block copolymer in a mass ratio of 75-90:10-25.

[0018] In this invention, the inner surface layer comprises a copolymer of polypropylene, polyolefin elastomer and styrene block copolymer in a mass ratio of 65-80:5-15:15-30.

[0019] In this invention, the phenylsilane coupling agent is selected from one of phenyltrimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, phenyltrichlorosilane, and N-phenyl-3-aminopropyltrimethoxysilane.

[0020] On the other hand, the present invention provides a method for preparing a high-barrier infusion membrane, comprising the following steps: (1) Layer material A and layer material B were prepared using a high-speed mixer and a twin-screw extruder, respectively; (2) Layer material A and layer material B are fed into different single screw extruders at the same time. The plasticized material after extrusion is fed into the manifold by the melt pump at the same time. In the manifold, layer material A and layer material B are stacked alternately. After passing through the multiplier, the stacked material forms the core layer material of alternating stacking. (3) The inner surface material and the outer surface material are respectively fed into different single screw extruders for plasticization. The plasticized inner surface material and the outer surface material are fed into the blown film die head together with the core material by the melt pump. After being extruded from the die head, the high barrier fluid delivery film is obtained after being blown, pulled and wound.

[0021] To address the technical problems of single-dimensional barrier or weak interfacial bonding caused by the modification of single inorganic fillers or simple compounding in existing technologies, this invention designs a binary filler system of modified kaolin and modified montmorillonite. Both fillers undergo targeted modification: the modified kaolin is modified with a phenylsilane coupling agent and nano-silica. On the one hand, the phenyl functional groups in the phenylsilane coupling agent can form good π-π interactions and interfacial compatibility with the styrene segments in the styrene block copolymer, significantly reducing the interfacial energy between the filler and the matrix and reducing interfacial defects. On the other hand, the nano-silica is loaded in situ onto the surface of the kaolin, which can effectively increase the surface roughness and specific surface area of ​​the kaolin, enhance its surface activity and reaction sites, and make the modified kaolin more uniformly dispersed in the matrix, with stronger interfacial bonding, and less prone to agglomeration and delamination. Modified montmorillonite is modified with quaternary ammonium salt and silane coupling agent. The quaternary ammonium salt cations can be inserted between the silicate layers of montmorillonite, significantly expanding the interlayer spacing through ion exchange and weakening the interlayer forces, which is conducive to the full intercalation and even partial exfoliation of montmorillonite in the polymer matrix. The silane coupling agent can covalently modify the edges and surface of montmorillonite, further improving its interfacial compatibility with styrene block copolymers, enhancing interfacial bonding strength, inhibiting filler agglomeration, and ensuring its uniform dispersion in the matrix. Modified kaolin and modified montmorillonite work together to form a hierarchical barrier structure consisting of large-sized sheet-like barriers and small-sized interlayer fillers. The large-sized modified kaolin serves as the main barrier unit, forming a continuous, highly tortuous sheet-like barrier skeleton in the matrix, effectively extending the permeation path of small molecules such as gases and water vapor, and significantly blocking their long-range diffusion and direct penetration. The small-sized modified montmorillonite can fully fill the gaps between the large-sized kaolin, the defects at the edge of the sheets, and the micropores of the polymer matrix itself, forming a secondary dense barrier network that blocks residual permeation channels and further reduces the permeation rate of the system.

[0022] Furthermore, existing technologies generally disperse inorganic fillers randomly throughout the polymer matrix of the core layer. However, this invention deliberately and uniquely confines the binary filler to the styrene block copolymer phase (layer material B) rather than the binary copolymer polypropylene phase (layer material A). The main reasons are: the compatibility of the modified binary filler with the styrene block copolymer is far superior to that with the binary copolymer polypropylene, which can reduce interface defects; at the same time, the difference in melt viscosity between the styrene block copolymer and the binary copolymer polypropylene can generate stronger interlayer shear forces during the alternating layering process, providing impetus for the hierarchical dispersion, synergistic exfoliation, and directional orientation of the binary filler; in addition, hierarchical dispersion can significantly increase the local concentration of the binary filler in the core layer, increasing the probability of the fillers interconnecting to form a dense barrier layer.

[0023] Since the layer material B is the dispersed phase of the composite filler, during the multi-layer co-extrusion and alternating layer stacking process, melt flow will generate interlayer shear force, and the single-layer thickness of the layer material B directly determines the degree of spatial confinement of the filler. If the ratio of dB to D1 and D2 is too large, the single layer of the layer material B is too thick, and the shear force cannot effectively act on the flaky filler. The modified kaolin is prone to disorderly accumulation and cannot be horizontally oriented along the film surface, making it difficult to form a continuous barrier skeleton, and the barrier effect is greatly attenuated. If the ratio is too small, the single-layer thickness is too thin, and the filler is prone to excessive extrusion. Not only can it not be regularly oriented, but it will also have problems such as agglomeration and fracture, damaging the structural uniformity of the film material. Therefore, the inventors found that the ratio of the single-layer thickness (dB) of the layer material B to the average particle diameter (D1) of the modified kaolin and the average particle diameter (D2) of the modified montmorillonite is the core parameter that determines the orientation effect and barrier performance of kaolin.

[0024] Based on this, the present invention defines the double matching ratio range of the single-layer thickness (dB) of the layer material B to the characteristic sizes (D1, D2) of the binary filler. When this ratio satisfies 1 < dB / D1 < 5 and 5 < dB / D2 < 25, the effective shear stress received by the kaolin in the confined space is maximized. The large-size composite modified kaolin can be fully peeled and horizontally oriented to construct a continuous barrier skeleton; the small-size modified montmorillonite can be evenly dispersed in the gaps between kaolin and the polymer matrix to fill the penetration channels, thereby constructing a dense inorganic barrier network and improving the barrier performance of the film material. If the number of layers is too small (such as 2 - 8 layers), the interlayer shear force is insufficient, and the binary filler cannot be effectively dispersed and oriented; if the number of layers is too large (such as more than 128 layers), the single-layer thicknesses of the layer material A and the layer material B are too thin, which will cause the layer structure to be unstable and the two phases to penetrate each other, damaging the synergistic barrier network.

[0025] The technical solution of the present invention has the following advantages and beneficial effects: The present invention realizes the hierarchical dispersion, synergistic peeling and directional orientation of the binary filler through the outer surface layer, the inner surface layer and the core layer structure composed of alternating layer stacking of the layer material A and the layer material B, and forms a multi-component synergistic barrier mechanism composed of the synergistic barrier of the binary filler, the interlayer shear orientation barrier and the hierarchical dispersion and concentration barrier, so as to improve the barrier performance of the infusion film. Specifically: The hierarchical structure of the binary filler blocks the straight gas penetration path and prolongs the penetration distance; the shear force generated by the alternating layer stacking makes the filler arranged directionally, further strengthening the barrier effect; the directional dispersion of the filler in the layer material B increases the local concentration and promotes the formation of a dense barrier layer; at the same time, the excellent interfacial bonding force between the modified filler and the styrene block copolymer avoids interfacial penetration, realizing the synergistic optimization of the barrier performance, mechanical properties and light transmittance, and significantly improving the barrier performance through the multi-component synergistic barrier mechanism.

[0026] The technical solution of the present invention has at least the following advantages and beneficial effects: 1. In this invention, modified kaolin and modified montmorillonite are combined to form a filler system, which is then confined and dispersed within a styrene block copolymer phase (layer material B) in the core layer. A micron-level confined space is constructed through an alternating layering process, achieving hierarchical dispersion, synergistic exfoliation, and directional orientation of the binary filler. This forms a multi-component synergistic barrier mechanism, resulting in a significant improvement in barrier performance. Simultaneously, it maintains excellent mechanical properties, permeability, and safety compatibility for infusion packaging, meeting the packaging requirements of small-sized formulations, amino acid infusions, and other infusion products with stringent high barrier requirements.

[0027] 2. This invention effectively avoids the problem of decreased mechanical properties and light transmittance caused by the agglomeration of single fillers by synergistic modification and dispersion of binary fillers in a specific layer. The tensile strength of the membrane material is maintained at 32-37 MPa, and the light transmittance is maintained at 86-92%, achieving synergistic optimization of high barrier properties, mechanical properties, and high light transmittance, thus overcoming the performance trade-off contradiction in existing technologies.

[0028] 3. This invention does not introduce barrier materials with defects such as EVOH, PA, and cyclic olefin polymers. The main material is a polypropylene and styrene block copolymer, which has high hygiene and safety, does not produce leachates, and meets the safety requirements for infusion packaging. At the same time, the modified kaolin of this invention is inexpensive, and the alternating layer blown film process can be realized by existing layer multipliers and co-extrusion blown film equipment without the need for additional large-scale equipment investment, which has good prospects for industrial application. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0030] Example 1 A high-barrier infusion membrane includes an outer surface layer, an inner surface layer, and a core layer. The core layer is composed of alternating layers of layer material A (binary copolymer polypropylene) and layer material B. Layer material B includes a styrene block copolymer, a styrene block copolymer grafted with maleic anhydride, and a composite filler. The composite filler includes modified kaolin and modified montmorillonite in a mass ratio of 4:1. The modified kaolin has an average sheet diameter (D1) of 2 μm and an aspect ratio of 100, while the modified montmorillonite has an average sheet diameter (D2) of 0.4 μm and an aspect ratio of 500.

[0031] The preparation method of modified kaolin is as follows: 5% of the total mass of kaolin and nano silica is dissolved in anhydrous ethanol, 1% of the mass of kaolin and nano silica is added, followed by the addition of kaolin. After stirring for 20 minutes, the mixture is filtered and thoroughly dried to remove the anhydrous ethanol, thus obtaining modified kaolin.

[0032] The modified montmorillonite was prepared as follows: montmorillonite was added to deionized water and ultrasonically dispersed for 45 min to obtain a montmorillonite suspension with a mass fraction of 3%; hexadecyltrimethylammonium bromide was added to the suspension at a molar ratio of 1:1 to the cation exchange capacity of montmorillonite, and stirred at 75°C for 3 h; then γ-aminopropyltriethoxysilane (8% of the mass of montmorillonite) was added, and stirring was continued for 4 h; after cooling, the mixture was filtered and washed until no bromide ions were found, dried, and ground through a 200-mesh sieve to obtain the modified montmorillonite.

[0033] Styrene block copolymer grafted with maleic anhydride was prepared by reactive extrusion. The specific steps were as follows: styrene block copolymer, maleic anhydride, and initiator (dicumyl peroxide) were added to an extruder at a mass ratio of 100:5:0.5. After reaction, the mixture was extruded as a strip, then granulated after water cooling. During reactive extrusion, the screw speed was 200 r / min, and the temperatures of each section of the twin-screw extruder were 160℃, 170℃, 175℃, 180℃, 180℃, 180℃, 185℃, 185℃, 185℃, and 180℃.

[0034] The preparation method of a high-barrier infusion membrane includes the following steps: (1) Layer material A and layer material B were prepared by using a high-speed mixer and a twin-screw extruder, respectively. When preparing core layer material B, the modified kaolin and modified montmorillonite were mixed evenly first, and then styrene block copolymer and styrene block copolymer grafted maleic anhydride were added for high-speed mixing at a speed of 800 r / min and a mixing time of 6 min. (2) Layer material A and layer material B are fed into different single-screw extruders at the same time. The plasticized material after extrusion is fed into the manifold by the melt pump at the same time. In the manifold, a stacked material of alternating layers of layer material A and layer material B is formed. The thickness ratio of layer material A to layer material B is 50:50. After passing through the multiplier, the stacked material forms a core layer material with 32 alternating layers. The temperature of the first and second zones of the extruder is 170℃, the temperature of the third to fifth zones is 200℃, the temperature of the sixth to tenth zones is 230℃, and the temperature of the manifold and multiplier is 240℃. (3) The inner and outer surface materials are fed into different single-screw extruders for plasticization; (4) After plasticization, the outer and inner surface materials are fed into the blown film die head together with the core material via a melt pump. After being extruded from the die head, the film is blown, cooled and shaped by water, drawn, and wound to obtain a high-barrier infusion film. The die head temperature is 200℃; the cooling water temperature is 15℃; and the blow-up ratio is 1.

[0035] The membrane preparation methods provided in Examples 2-5 are the same as those in Example 1.

[0036] The components and formulations of the membrane materials in Examples 1-5 are shown in Table 1.

[0037] Table 1. Components and proportions in Examples 1-5

[0038] In the above embodiments, by adjusting the number of alternating layers of material A and material B in the core layer, core layers with different numbers of alternating layers were obtained. In Examples 1-5, the number of layers in the alternating core layer structures were 16, 32, 64, 64, and 64, respectively. Using the thickness ratio, the total thickness of the film material, and the number of layers in the alternating layer structure, the thicknesses of the outer surface layer, the inner surface layer, and individual layers A and B can be calculated, thereby obtaining the ratios d_B / D1 and d_B / D2, as shown in Table 2.

[0039] Table 2. Number of alternating layers and related parameters of the membrane core layer in Examples 1-5

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that layer material B contains only modified kaolin, while the rest is the same as in Example 1.

[0041] Comparative Example 2 The difference between this comparative example and Example 1 is that the core material is a composition of binary copolymer polypropylene and styrene block copolymer in a mass ratio of 50:50, while the rest is the same as in Example 1.

[0042] Comparative Example 3 The difference between this comparative example and Example 1 is that layer material B contains only modified montmorillonite, while the rest is the same as in Example 1.

[0043] Comparative Example 4 The difference between this comparative example and Example 1 is that the mass ratio of modified kaolin to modified montmorillonite in the composite filler used in layer material B is 1:1, while the rest is the same as in Example 1.

[0044] Comparative Examples 5-9 The difference between Comparative Examples 5-9 and Example 1 is that the number of alternating layers of core material A and layer material B is 2, 4, 8, 128, and 256, respectively, while the rest is the same as in Example 1.

[0045] Comparative Example 10 The difference between this comparative example and Example 1 is that in layer material B, the modified kaolin is prepared by dissolving 5% (by weight of kaolin) of phenylsilane coupling agent in anhydrous ethanol, adding kaolin, stirring for 20 minutes, filtering, and thoroughly drying to remove the anhydrous ethanol, thus obtaining the modified kaolin. The rest is the same as in Example 1.

[0046] Comparative Example 11 The difference between this comparative example and Example 1 is as follows: In layer material B, the modified montmorillonite is prepared by adding montmorillonite to deionized water and ultrasonically dispersing it for 45 minutes to obtain a 3% (w / w) montmorillonite suspension. γ-aminopropyltriethoxysilane (8% of the montmorillonite mass) is then added to the suspension, and stirring continues for 4 hours. After cooling, the mixture is filtered and washed until no bromide ions are present. After drying, it is ground through a 200-mesh sieve to obtain the modified montmorillonite. The rest is the same as in Example 1.

[0047] Comparative Example 12 The difference between this comparative example and Example 1 is that modified kaolin and modified montmorillonite are added to layer material A (binary copolymer polypropylene) instead of layer material B. Everything else is the same as in Example 1.

[0048] Comparative Example 13 This comparative example uses ordinary blending to prepare a single core layer material, which is a mixture of layer material A and layer material B in Example 1. Then, a three-layer co-extrusion blown film process is used to prepare a three-layer co-extruded film, and the composition and thickness ratio of the outer and inner layers are the same as those in Example 1.

[0049] Experimental Example The membrane materials of the examples and comparative examples were tested for oxygen transmission rate, water vapor transmission rate, tensile strength, and light transmittance. The test methods are as follows: Water vapor transmission rate: Determined at 38℃ and 90% relative humidity according to the first method of water vapor transmission rate determination (YBB00092003-2015).

[0050] Oxygen permeability: Determined at 23℃ and 50% relative humidity according to the first method of gas permeability determination (YBB00082003-2015).

[0051] Tensile strength: Tested at 25℃, according to the tensile property test method (YBB00082003-2015), using type II specimens, and at a test speed of 500 mm / min.

[0052] Transmittance: The transmittance was measured at a wavelength of 450 nm using the ultraviolet-visible spectrophotometry method (Chinese Pharmacopoeia 2025).

[0053] The test results are shown in Table 3 below.

[0054] Table 3 Performance test results of the examples and comparative examples

[0055] From the data in Table 3, we can see that: Examples 1-5 used a binary filler system composed of modified kaolin and modified montmorillonite. The water vapor transmission rate and oxygen transmission rate of this system were significantly lower than those of Comparative Example 1 (modified kaolin only) and Comparative Example 3 (modified montmorillonite only), which contained only a single modified filler. For example, the water vapor transmission rate of Example 1 was 0.30 g / (m³). 2 •24h) Comparison Example 1 (1.23g / (m 2 The concentration of 24h decreased by 75.6%, compared to control 3 (0.93g / (m 2 • 24h) decreased by 67.7%; oxygen permeability (63cm) 3 / (m 2 ·24h·0.1MPa) Comparison Example 1 (610cm) 3 / (m 2 The pressure (24h, 0.1MPa) decreased by 89.7%, compared to control example 3 (503cm). 3 / (m 2 The pressure was reduced by 87.4% over 24 hours (0.1 MPa), demonstrating that the synergistic barrier effect of the binary packing is significant and far exceeds that of the single modified packing.

[0056] Comparative Example 4 used a composite filler of modified kaolin and modified montmorillonite in a mass ratio of 1:1. Its barrier performance was much lower than that of Example 1, indicating that the specific mixing ratio of modified kaolin and modified montmorillonite (3-5:1) is the key to achieving synergistic barrier. An improper ratio will destroy the hierarchical barrier structure and reduce the synergistic effect.

[0057] Comparative Examples 5-8 (2-8 layers) exhibited poor barrier properties, as well as unsatisfactory mechanical properties and light transmittance. This was attributed to insufficient interlayer shear force due to the low number of layers, preventing effective dispersion and orientation of the binary filler. Comparative Examples 8 and 9 (128 and 256 layers, respectively) also showed significantly reduced barrier properties due to layer structure instability and interpenetration between the two phases, disrupting the synergistic barrier network. Examples 1-5 (16-64 layers) demonstrated the best barrier properties, mechanical properties, and light transmittance, indicating that this range of layer numbers and corresponding size matching can regulate the dispersion of the binary filler in layer material B, promoting uniform dispersion of the binary filler within the material.

[0058] Comparative Example 10 modified kaolin using only phenylsilane coupling agent, and Comparative Example 11 modified montmorillonite using only γ-aminopropyltriethoxysilane. Their water vapor permeability and oxygen permeability were significantly higher than those of Example 1. This indicates that the composite fillers modified with phenylsilane coupling agent and nano-silica, and modified with quaternary ammonium salt and silane coupling agent, have a synergistic promoting effect, which can improve the barrier properties of the materials.

[0059] Comparative Example 12, where the composite filler was dispersed in core material A (binary copolymer polypropylene), showed significantly lower barrier properties, mechanical properties, and light transmittance compared to Example 1. This indicates that after modification, the phenyl functional groups in the phenylsilane coupling agent can form good π-π interactions and interfacial compatibility with the styrene segments in the styrene block copolymer, significantly reducing the interfacial energy between the filler and the matrix, minimizing interfacial defects, and facilitating the uniform dispersion of the filler in the styrene block copolymer.

[0060] Comparative Example 13 uses ordinary blending to prepare a single core layer material, which does not form an alternating layered structure like in Example 1. The filler dispersion and orientation are poor, so the barrier properties, mechanical properties and light transmittance are all lower than those of Example 1.

[0061] The tensile strength (32-37 MPa) and light transmittance (86%-92%) of Examples 1-5 are significantly improved compared with Comparative Examples 1, 3, 4 and 13, and only slightly lower than Comparative Example 2 (without filler), indicating that the method of the present invention can simultaneously improve the barrier properties, mechanical properties and light transmittance of the material.

[0062] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-barrier infusion membrane, characterized in that, It includes an outer surface layer, an inner surface layer, and a core layer, wherein the core layer is composed of alternating layers of layer material A and layer material B; The layer material A comprises binary copolymer polypropylene; The layer material B includes styrene block copolymer, styrene block copolymer grafted maleic anhydride and composite filler, wherein the composite filler includes modified kaolin and modified montmorillonite; The modified kaolin is kaolin modified with phenylsilane coupling agent and nano-silica; The modified montmorillonite is montmorillonite modified with hexadecyltrimethylammonium bromide and γ-aminopropyltriethylsilane.

2. The high-barrier infusion membrane according to claim 1, characterized in that, The mass ratio of the styrene block copolymer, the styrene block copolymer grafted with maleic anhydride, and the composite filler is 75-90:5-20:0.5-8, and the mass ratio of modified kaolin and modified montmorillonite in the composite filler is 3-5:

1.

3. The high-barrier infusion membrane according to claim 1, characterized in that, The nano-silica has a particle size of 5-20 nm, the nano-silica has a loading amount of 0.5-2% on kaolin, and the modified montmorillonite has an interlayer spacing of 2-3.5 nm. The modified kaolin has an average sheet diameter D1 of 1-3 μm and a diameter-to-thickness ratio of 50-100, while the modified montmorillonite has an average sheet diameter D2 of 0.1-1 μm and a diameter-to-thickness ratio of 100-1000. The single-layer thickness d_B of the layer material B is 2-10 μm, where 1 <d_B / D1<5,5<d_B / D2<25。 4. The high-barrier infusion membrane according to claim 1, characterized in that, The thickness of the high-barrier infusion membrane is 150-250 μm, and the thickness ratio of the inner surface layer, core layer and outer surface layer is 15-30:45-70:10-25; The thickness ratio of layer material A to layer material B is 35-65:35-65, and the number of alternating layers is 2. n , where n is 4-6.

5. The high-barrier infusion membrane according to claim 1, characterized in that, The outer layer comprises homopolymer polypropylene and styrene block copolymer in a mass ratio of 75-90:10-25.

6. The high-barrier infusion membrane according to claim 1, characterized in that, The inner surface layer comprises a copolymer of polypropylene, polyolefin elastomer and styrene block copolymer in a mass ratio of 65-80:5-15:15-30.

7. The high-barrier infusion membrane according to claim 1, characterized in that, The phenylsilane coupling agent is selected from one of phenyltrimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, phenyltrichlorosilane, and N-phenyl-3-aminopropyltrimethoxysilane.

8. The method for preparing a high-barrier infusion membrane according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Layer material A and layer material B were prepared using a high-speed mixer and a twin-screw extruder, respectively; (2) Layer material A and layer material B are fed into different single screw extruders at the same time. The plasticized material after extrusion is fed into the manifold by the melt pump at the same time. In the manifold, layer material A and layer material B are stacked alternately. After passing through the multiplier, the stacked material forms the core layer material of alternating stacking. (3) The inner surface material and the outer surface material are respectively fed into different single screw extruders for plasticization. The plasticized inner surface material and the outer surface material are fed into the blown film die head together with the core material by the melt pump. After being extruded from the die head, the high barrier fluid delivery film is obtained after being blown, pulled and wound.

Images