Low-temperature-resistant high-toughness three-layer infusion film and preparation method thereof

Abstract

The invention relates to the technical field of infusion films, and provides a low-temperature-resistant high-toughness three-layer infusion film and a preparation method thereof. The low-temperature-resistant high-toughness three-layer infusion film sequentially comprises an inner layer, a middle layer and an outer layer from inside to outside, wherein the inner layer is prepared from the following raw materials in parts by weight: 30 to 40 parts of metallocene polyethylene, 5 to 15 parts of ultralow-density polyethylene and 50 to 60 parts of high-density polyethylene; the middle layer is prepared from the following raw materials in parts by weight: 25 to 30 parts of linear polyethylene, 10 to 15 parts of hydrogenated styrene-butadiene block copolymer, 40 to 60 parts of high-density polyethylene and 2 to 10 parts of cross-linked modified polyethylene; and the outer layer is prepared from the following raw materials in parts by weight: 20-40 parts of linear polyethylene, 5-15 parts of ultra-low density polyethylene and 55-65 parts of high density polyethylene. The three-layer infusion film provided by the invention is convenient and safe to use, and has the effects of low temperature resistance, high toughness, low cost, energy conservation and environmental protection.

Description

Technical Field

[0001] The present invention belongs to the technical field of infusion films, and in particular, relates to a low-temperature-resistant and high-toughness three-layer infusion film and a preparation method thereof. Background Art

[0002] Three-layer co-extruded infusion membranes are widely used in the medical field. They are made of three layers of polymer films with different functions through a co-extrusion process. The three layers usually include a barrier layer and two structural layers. The barrier layer mainly prevents drug penetration and contamination, while the structural layer provides the necessary mechanical strength and stability. In the prior art, three-layer infusion membranes mostly use a blend of polypropylene and elastomer.

[0003] For example, the patent with publication number CN113954469A discloses a three-layer co-extruded polyolefin infusion membrane and its preparation method. The polyethylene, polypropylene and SEBS materials used are all medical-grade materials, ensuring that the product can be in direct contact with the drug and that the materials have good compatibility and bonding. The inner sealing layer includes chitosan antibacterial modified polypropylene, which improves the antibacterial properties of the infusion membrane and is beneficial to the safety and stability of infusion drugs during use. It does not require radiation cross-linking or the use of adhesives, and uses a full-process automatic control system and fault alarm system, so it can be used for large-scale industrial use.

[0004] Another example is the patent with publication number CN116674272A, which discloses a three-layer co-extruded infusion film for a liquid-liquid multi-chamber bag and a preparation method thereof, including a three-layer structure consisting of an outer layer, a middle layer and an inner layer; the outer layer material is a mixture of homopolymer polypropylene, ethylene-propylene polymer with low ethylene content and SEBS or SEPS; the middle layer material is a mixture of ethylene-propylene polymer with high ethylene content, ethylene-propylene polymer with low ethylene content and SEBS or SEPS; the inner layer material is a mixture of ethylene-propylene-butene polymer, ethylene-propylene polymer with high ethylene content, ethylene-propylene polymer with low ethylene content and SEBS or SEPS. The provided infusion film has excellent flexibility, stable solid welding strength and weak welding strength.

[0005] However, the three-layer infusion membrane adopts a blend system of polypropylene and elastomer, which has the following defects: the material has poor flexibility, the infusion bag becomes brittle after high-temperature steam sterilization, and is prone to falling and breakage and pressurized leakage in actual use; the low-temperature impact resistance is poor, especially for large-sized infusion bags, the probability of damage and leakage during low-temperature transportation is greatly increased. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the first object of the present invention is to provide a low-temperature resistant and high-toughness three-layer infusion membrane, which is easy and safe to use and has the effects of low-temperature resistance, high toughness, low cost, energy saving and environmental protection.

[0007] The present invention is achieved through the following technical solutions:

[0008] A three-layer infusion film with low temperature resistance and high toughness, which comprises an inner layer, a middle layer and an outer layer from the inside to the outside; wherein:

[0009] The inner layer is composed of the following raw materials in parts by weight: 30-40 parts of metallocene polyethylene, 5-15 parts of ultra-low density polyethylene, and 50-60 parts of high-density polyethylene;

[0010] The middle layer is composed of the following raw materials in parts by weight: 25-30 parts of linear polyethylene, 10-15 parts of hydrogenated styrene-butadiene block copolymer, 40-60 parts of high-density polyethylene, and 2-10 parts of cross-linked modified polyethylene;

[0011] The outer layer is composed of the following raw materials in parts by weight: 20-40 parts of linear polyethylene, 5-15 parts of ultra-low density polyethylene, and 55-65 parts of high-density polyethylene.

[0012] The technical mechanism of the present invention lies in that, on the one hand, the polyethylene system formula is adopted, so that the three-layer film as a whole has better flexibility, avoiding damage caused by falling after sterilization. At the same time, the introduction of the inner layer of metallocene polyethylene makes the heat sealing strength higher, avoiding leakage under pressure; the polyethylene pellets have better low-temperature resistance, avoiding damage and leakage during low-temperature transportation.

[0013] On the other hand, the addition of cross-linked modified polyethylene plays a vital role in the low-temperature-resistant and high-toughness three-layer infusion membrane.

[0014] First, cross-linked polyethylene is modified by chemical or physical methods to form cross-linked bonds between polyethylene molecular chains, thereby changing the molecular structure of polyethylene. This structural change makes cross-linked polyethylene have higher heat resistance and low temperature resistance. This feature is particularly important in infusion membranes, because infusion membranes need to maintain stable performance under different temperature environments. The addition of cross-linked polyethylene can effectively increase the heat resistance temperature of the membrane, making it less likely to deform or break at high temperatures. At the same time, it can also enhance the low temperature resistance of the membrane, ensuring that the membrane material will not break due to embrittlement during low-temperature transportation or storage.

[0015] Secondly, the addition of cross-linked modified polyethylene can also significantly enhance the toughness and strength of the membrane. Due to the formation of cross-linked bonds, the interaction between polyethylene molecular chains is enhanced, making the membrane less likely to break or tear when subjected to external forces. This feature is crucial for infusion membranes, as they need to withstand a certain amount of pressure and tension to ensure that they will not be damaged by external forces during the infusion process.

[0016] Thirdly, the addition of cross-linked modified polyethylene can also improve the processing properties of the film. During the melt extrusion process, the molecular chains of the cross-linked modified polyethylene are more easily stretched and oriented, which is conducive to the formation of a more uniform and denser film material. In addition, the cross-linked modified polyethylene can also increase the viscosity of the melt, making it easier to control the shape and thickness of the film during the extrusion process.

[0017] Finally, the addition of cross-linked modified polyethylene can also improve the barrier properties of the film. Due to the formation of cross-linked bonds, the gaps between polyethylene molecular chains are reduced, which enhances the barrier properties of the film to substances such as gas and moisture. This is also very important for infusion membranes because it needs to prevent external substances from contaminating the infusion liquid.

[0018] Furthermore, the thickness of the inner layer is 30-40um, the thickness of the middle layer is 140-150um, and the thickness of the outer layer is 30-40um.

[0019] Furthermore, the metallocene polyethylene used in the inner layer has a melting point of 110-130°C and a density of 0.92-0.95 g / cm 3 , a melt index of 0.5-1.5 g / 10 min; and / or,

[0020] The ultra-low density polyethylene used in the inner layer has a melting point of 110-120°C and a density of 0.89-0.92 g / cm 3 , a melt index of 0.2-0.8 g / 10 min; and / or,

[0021] The high-density polyethylene used in the inner layer has a melting point of 120-140°C and a density of 0.94-0.97 g / cm 3 , the melt index is 0.4-0.8g / 10min.

[0022] Furthermore, the linear polyethylene used in the middle layer has a melting point of 105-120°C and a density of 0.9-0.95 g / cm 3 , a melt index of 1.5-2.5 g / 10 min; and / or,

[0023] The density of the hydrogenated styrene-butadiene block copolymer used in the middle layer is 0.9-0.95 g / cm 3, a melt index of 2.0-3.5 g / 10 min; and / or,

[0024] The high-density polyethylene used in the middle layer has a melting point of 120-140°C and a density of 0.94-0.97 g / cm 3 , the melt index is 0.4-0.8g / 10min.

[0025] Furthermore, the linear polyethylene used in the outer layer has a melting point of 105-120°C and a density of 0.9-0.95 g / cm 3 , a melt index of 1.5-2.5 g / 10 min; and / or,

[0026] The ultra-low density polyethylene used in the outer layer has a melting point of 110-120°C and a density of 0.89-0.92 g / cm 3 , a melt index of 0.2-0.8 g / 10 min; and / or,

[0027] The high-density polyethylene used in the outer layer has a melting point of 120-140°C and a density of 0.94-0.97 g / cm 3 , the melt index is 0.4-0.8g / 10min.

[0028] Furthermore, the cross-linked modified polyethylene is composed of the following raw materials in parts by weight: 80-98 parts of linear polyethylene, 1-10 parts of vinyltrimethoxysilane, 0.05-0.5 parts of dibenzoyl peroxide, 0.02-0.15 parts of dibutyltin dilaurate, 0-1 parts of hindered phenol antioxidant, and 1-5 parts of nano calcium carbonate.

[0029] Linear polyethylene is used as the base material and provides the main properties of polyethylene.

[0030] Vinyltrimethoxysilane acts as a crosslinking agent and undergoes a grafting reaction with linear polyethylene to form a crosslinking structure.

[0031] Benzoyl peroxide acts as an initiator, which decomposes under heat to form free radicals, initiating a cross-linking reaction.

[0032] Dibutyltin dilaurate is used as a catalyst to promote the cross-linking reaction between silane and polyethylene.

[0033] Hindered phenol antioxidants are used to improve the antioxidant properties of polyethylene and extend its service life.

[0034] Nano calcium carbonate, as a nano filler in polyethylene materials, can enhance the interaction force of polymer molecular chains, thereby improving the strength and toughness of the material.

[0035] Furthermore, the three-layer infusion membrane satisfies at least one of the following properties:

[0036] Water vapor transmission rate ≥1.8g / (m 2 24h);

[0037] Oxygen permeability ≥860cm 3 / (m 2 ·24h·0.1MPa);

[0038] Heat sealing strength ≥40N / 15mm;

[0039] Longitudinal tensile strength ≥39MPa, transverse tensile strength ≥38MPa;

[0040] Longitudinal elongation at break ≥ 690%, transverse elongation at break ≥ 570%;

[0041] There is no leakage or damage during pressurization;

[0042] After being frozen at zero degrees for 48 hours, it dropped from 2 meters without any leakage or damage.

[0043] The second object of the present invention is to provide a method for preparing the above-mentioned low-temperature resistant and high-toughness three-layer infusion film, comprising the following steps:

[0044] S1, blending and granulating the metallocene polyethylene, ultra-low density polyethylene and high-density polyethylene to obtain inner layer pellets;

[0045] S2, blending and granulating the linear polyethylene, hydrogenated styrene-butadiene block copolymer, high-density polyethylene and cross-linked modified polyethylene to obtain middle-layer pellets;

[0046] S3, blending and granulating the linear polyethylene, ultra-low density polyethylene and high-density polyethylene to obtain outer layer pellets;

[0047] S4, using a bottom-blowing water-cooled three-layer co-extrusion film blowing machine for processing, and heating up the inner layer, middle layer and outer layer host machine;

[0048] S5, adding the pellets of each layer into the corresponding main machine hopper respectively, and carrying out film blowing production to obtain the three-layer infusion film.

[0049] Furthermore, the temperature of the inner layer main machine is 160-210°C, the temperature of the middle layer main machine is 160-210°C, the temperature of the outer layer main machine is 160-210°C, and the die head temperature is 170-190°C.

[0050] Furthermore, in step S2, the method for preparing the cross-linked modified polyethylene comprises:

[0051] ss1: linear polyethylene, vinyl trimethoxysilane, dibenzoyl peroxide, dibutyltin dilaurate, hindered phenol antioxidant and nano calcium carbonate are mixed to obtain a mixture;

[0052] ss2 melt-extrude the mixture and control the temperature of the melt-extruded material to be 180-220° C. to carry out a cross-linking reaction to obtain a cross-linked modified polyethylene.

[0053] During the extrusion process, the raw materials are melted and mixed under the high temperature of the extruder, and dibenzoyl peroxide is thermally decomposed to form free radicals. In the subsequent section of the extruder, the temperature of the molten extruded material is controlled at 180-220°C, so that the free radicals react with vinyl trimethoxysilane to form a cross-linked structure. Dibutyltin dilaurate is used as a catalyst to promote the cross-linking reaction. After the cross-linking reaction is completed, the material is cooled and shaped to obtain a cross-linked modified polyethylene product.

[0054] By chemically modifying the polyethylene molecular chains to form a cross-linked structure, its heat resistance and mechanical properties can be improved.

[0055] The beneficial effects of the present invention are:

[0056] (1) The introduction of polyethylene granules (including metallocene polyethylene, ultra-low density polyethylene and high-density polyethylene) makes the membrane material have excellent low-temperature resistance, avoiding damage and leakage during low-temperature transportation.

[0057] (2) The three-layer structure design and the addition of raw materials such as hydrogenated styrene-butadiene block copolymer make the film material more tough and improve its tear and impact resistance. At the same time, the introduction of the inner layer of metallocene polyethylene makes the heat sealing strength of the film material higher, avoiding the problem of pressurized leakage.

[0058] (3) The polyethylene system formula is adopted to reduce the raw material cost and improve the production efficiency. At the same time, no harmful substances are required in the preparation process, which meets the environmental protection requirements.

[0059] (4) The three-layer infusion film obtained by the present invention meets the following properties: water vapor permeability ≥ 1.8 g / (m 2 ·24h); oxygen transmission rate ≥860cm 3 / (m 2 ·24h·0.1MPa); heat sealing strength ≥40N / 15mm; longitudinal tensile strength ≥39MPa, transverse tensile strength ≥38MPa; longitudinal elongation at break ≥690%, transverse elongation at break ≥570%; no leakage or breakage under pressure; after freezing at zero degrees for 48 hours, no leakage or breakage after falling from 2 meters. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0061] Figure 1 This is a schematic diagram of the structure of the three-layer infusion membrane provided by the present invention. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0063] Example 1

[0064] The three-layer infusion film with low temperature resistance and high toughness provided in this embodiment includes an inner layer, a middle layer and an outer layer from the inside to the outside; wherein:

[0065] The inner layer is composed of the following raw materials in parts by weight: 30 parts of metallocene polyethylene, 10 parts of ultra-low density polyethylene, and 60 parts of high-density polyethylene.

[0066] The middle layer is composed of the following raw materials in parts by weight: 38 parts of linear polyethylene, 10 parts of SEBS, 50 parts of high-density polyethylene, and 2 parts of cross-linked modified polyethylene.

[0067] The outer layer is composed of the following raw materials in parts by weight: 30 parts of linear polyethylene, 10 parts of ultra-low density polyethylene, and 60 parts of high-density polyethylene.

[0068] The thickness of the inner layer is 30um, the thickness of the middle layer is 150um, and the thickness of the outer layer is 30um.

[0069] The metallocene polyethylene used in the inner layer has a melting point of 127°C and a density of 0.92 g / cm 3 , melt index is 0.4g / 10min; the melting point of ultra-low density polyethylene is 115℃, and the density is 0.90g / cm 3 , melt index is 0.3g / 10min; the melting point of high-density polyethylene is 135℃, and the density is 0.96g / cm 3 , the melt index is 0.4g / 10min.

[0070] The linear polyethylene used in the middle layer has a melting point of 113°C and a density of 0.926 g / cm 3 , melt index is 2g / 10min; SEBS density is 0.91g / cm 3 , melt index is 2.6g / 10min; the melting point of high-density polyethylene is 135℃, and the density is 0.96g / cm 3 , the melt index is 0.4g / 10min.

[0071] The cross-linked modified polyethylene is composed of the following raw materials in parts by weight: 83.4 parts of linear polyethylene, 10 parts of vinyl trimethoxy silane, 0.5 parts of dibenzoyl peroxide, 0.1 parts of dibutyltin dilaurate, 1 part of antioxidant 264 (BHT), and 5 parts of nano calcium carbonate.

[0072] The linear polyethylene used in the outer layer has a melting point of 113°C and a density of 0.926 g / cm 3 , melt index is 2g / 10min; the melting point of ultra-low density polyethylene is 115℃, and the density is 0.90g / cm 3 , melt index is 0.3g / 10min; the melting point of high-density polyethylene is 135℃, and the density is 0.96g / cm 3 , the melt index is 0.4g / 10min.

[0073] The production process of the low-temperature-resistant and high-toughness three-layer infusion film comprises the following steps:

[0074] 1. The pellets required for the inner, middle and outer layers are blended and granulated through a twin-screw extruder.

[0075] 2. Use a downward-blowing water-cooled three-layer co-extrusion film blowing machine for processing, and heat up the inner, middle and outer layers.

[0076] 3. Add each layer of pellets into the corresponding main machine hopper for film blowing production.

[0077] 4. The temperature of the inner layer main machine is 160-210℃, the temperature of the middle layer main machine is 160-210℃, the temperature of the outer layer main machine is 160-210℃, and the temperature of the die head is 170-190℃.

[0078] 5. The preparation method of the cross-linked modified polyethylene comprises: mixing linear polyethylene, vinyl trimethoxysilane, dibenzoyl peroxide, dibutyltin dilaurate, hindered phenol antioxidant and nano-calcium carbonate to obtain a mixture; melt-extruding the mixture and controlling the temperature of the melt extrusion to 180°C to perform a cross-linking reaction to obtain a cross-linked modified polyethylene.

[0079] The performance test was carried out according to the multi-layer co-extrusion infusion film standard in the YBB standard, and the results are as follows:

[0080] Water vapor transmission rate: 1.8g / (m 2 ·24h).

[0081] Oxygen permeability: 862.78cm 3 / (m 2 ·24h·0.1MPa);

[0082] Heat sealing strength: 42N / 15mm.

[0083] Tensile strength: 39MPa in longitudinal direction, 38MPa in transverse direction.

[0084] Elongation at break: 697% longitudinally, 570% transversely.

[0085] There was no leakage or damage during pressurization.

[0086] After being frozen at zero degrees for 48 hours, it dropped from 2 meters without any leakage or damage.

[0087] Example 2

[0088] The three-layer infusion film with low temperature resistance and high toughness provided in this embodiment includes an inner layer, a middle layer and an outer layer from the inside to the outside; wherein:

[0089] The inner layer is composed of the following raw materials in parts by weight: 40 parts of metallocene polyethylene, 10 parts of ultra-low density polyethylene, and 50 parts of high-density polyethylene.

[0090] The middle layer is composed of the following raw materials in parts by weight: 25 parts of linear polyethylene, 15 parts of SEBS, 55 parts of high-density polyethylene, and 5 parts of cross-linked modified polyethylene.

[0091] The outer layer is composed of the following raw materials in parts by weight: 25 parts of linear polyethylene, 10 parts of ultra-low density polyethylene, and 65 parts of high-density polyethylene.

[0092] The thickness of the inner layer is 30um, the thickness of the middle layer is 150um, and the thickness of the outer layer is 30um.

[0093] The metallocene polyethylene used in the inner layer has a melting point of 127°C and a density of 0.92 g / cm 3 , melt index is 0.4g / 10min; the melting point of ultra-low density polyethylene is 115℃, and the density is 0.90g / cm 3 , melt index is 0.3g / 10min; the melting point of high-density polyethylene is 135℃, and the density is 0.96g / cm 3 , the melt index is 0.4g / 10min.

[0094] The linear polyethylene used in the middle layer has a melting point of 113°C and a density of 0.926 g / cm 3 , melt index is 2g / 10min; SEBS density is 0.91g / cm 3 , melt index is 2.6g / 10min; the melting point of high-density polyethylene is 135℃, and the density is 0.96g / cm 3 , the melt index is 0.4g / 10min.

[0095] The cross-linked modified polyethylene is composed of the following raw materials in parts by weight: 91 parts of linear polyethylene, 5 parts of vinyl trimethoxy silane, 0.25 parts of dibenzoyl peroxide, 0.10 parts of dibutyltin dilaurate, 0.65 parts of hindered phenol antioxidant, and 3 parts of nano calcium carbonate.

[0096] The linear polyethylene used in the outer layer has a melting point of 113°C and a density of 0.926 g / cm 3 , melt index is 2g / 10min; the melting point of ultra-low density polyethylene is 115℃, and the density is 0.90g / cm 3 , melt index is 0.3g / 10min; the melting point of high-density polyethylene is 135℃, and the density is 0.96g / cm 3 , the melt index is 0.4g / 10min.

[0097] The production process of the low-temperature-resistant and high-toughness three-layer infusion film comprises the following steps:

[0098] 1. The pellets required for the inner, middle and outer layers are blended and granulated through a twin-screw extruder.

[0099] 2. Use a downward-blowing water-cooled three-layer co-extrusion film blowing machine for processing, and heat up the inner, middle and outer layers.

[0100] 3. Add each layer of pellets into the corresponding main machine hopper for film blowing production.

[0101] 4. The temperature of the inner layer main machine is 160-210℃, the temperature of the middle layer main machine is 160-210℃, the temperature of the outer layer main machine is 160-210℃, and the temperature of the die head is 170-190℃.

[0102] 5. The preparation method of the cross-linked modified polyethylene comprises: mixing linear polyethylene, vinyl trimethoxysilane, dibenzoyl peroxide, dibutyltin dilaurate, hindered phenol antioxidant and nano-calcium carbonate to obtain a mixture; melt-extruding the mixture and controlling the temperature of the melt extrusion to 200°C to perform a cross-linking reaction to obtain a cross-linked modified polyethylene.

[0103] The performance test was carried out according to the multi-layer co-extrusion infusion film standard in the YBB standard, and the results are as follows:

[0104] Water vapor transmission rate: 2.0g / (m 2 ·24h).

[0105] Oxygen permeability: 892.78cm 3 / (m 2 ·24h·0.1MPa).

[0106] Heat sealing strength: 40N / 15mm.

[0107] Tensile strength: 40MPa in longitudinal direction, 39MPa in transverse direction.

[0108] Elongation at break: 715% longitudinally, 590% transversely.

[0109] There is no leakage or damage during pressurization;

[0110] After being frozen at zero degrees for 48 hours, it dropped from 2 meters without any leakage or damage.

[0111] Example 3

[0112] The three-layer infusion film with low temperature resistance and high toughness provided in this embodiment includes an inner layer, a middle layer and an outer layer from the inside to the outside; wherein:

[0113] The inner layer is composed of the following raw materials in parts by weight: 35 parts of metallocene polyethylene, 10 parts of ultra-low density polyethylene, and 55 parts of high-density polyethylene.

[0114] The middle layer is composed of the following raw materials in parts by weight: 25 parts of linear polyethylene, 10 parts of SEBS, 55 parts of high-density polyethylene, and 10 parts of cross-linked modified polyethylene.

[0115] The outer layer is composed of the following raw materials in parts by weight: 35 parts of linear polyethylene, 10 parts of ultra-low density polyethylene, and 55 parts of high-density polyethylene.

[0116] The thickness of the inner layer is 30um, the thickness of the middle layer is 150um, and the thickness of the outer layer is 30um.

[0117] The metallocene polyethylene used in the inner layer has a melting point of 127°C and a density of 0.92 g / cm 3 , melt index is 0.4g / 10min; the melting point of ultra-low density polyethylene is 115℃, and the density is 0.90g / cm 3 , melt index is 0.3g / 10min; the melting point of high-density polyethylene is 135℃, and the density is 0.96g / cm 3 , the melt index is 0.4g / 10min.

[0118] The linear polyethylene used in the middle layer has a melting point of 113°C and a density of 0.926 g / cm 3 , melt index is 2g / 10min; SEBS density is 0.91g / cm 3 , melt index is 2.6g / 10min; the melting point of high-density polyethylene is 135℃, and the density is 0.96g / cm 3 , the melt index is 0.4g / 10min.

[0119] The cross-linked modified polyethylene is composed of the following raw materials in parts by weight: 97.93 parts of linear polyethylene, 1 part of vinyltrimethoxysilane, 0.05 parts of dibenzoyl peroxide, 0.02 parts of dibutyltin dilaurate, and 1 part of nano calcium carbonate.

[0120] The linear polyethylene used in the outer layer has a melting point of 113°C and a density of 0.926 g / cm 3 , melt index is 2g / 10min; the melting point of ultra-low density polyethylene is 115℃, and the density is 0.90g / cm 3 , melt index is 0.3g / 10min; the melting point of high-density polyethylene is 135℃, and the density is 0.96g / cm 3 , the melt index is 0.4g / 10min.

[0121] The production process of the low-temperature-resistant and high-toughness three-layer infusion film comprises the following steps:

[0122] 1. The pellets required for the inner, middle and outer layers are blended and granulated through a twin-screw extruder.

[0123] 2. Use a downward-blowing water-cooled three-layer co-extrusion film blowing machine for processing, and heat up the inner, middle and outer layers.

[0124] 3. Add each layer of pellets into the corresponding main machine hopper for film blowing production.

[0125] 4. The temperature of the inner layer main machine is 160-210℃, the temperature of the middle layer main machine is 160-210℃, the temperature of the outer layer main machine is 160-210℃, and the temperature of the die head is 170-190℃.

[0126] 5. The preparation method of the cross-linked modified polyethylene comprises: mixing linear polyethylene, vinyl trimethoxysilane, dibenzoyl peroxide, dibutyltin dilaurate, hindered phenol antioxidant and nano-calcium carbonate to obtain a mixture; melt-extruding the mixture and controlling the temperature of the melt extrusion to 220°C to perform a cross-linking reaction to obtain a cross-linked modified polyethylene.

[0127] The performance test was carried out according to the multi-layer co-extrusion infusion film standard in the YBB standard, and the results are as follows:

[0128] Water vapor transmission rate: 1.93g / (m 2 ·24h).

[0129] Oxygen permeability: 878.36cm 3 / (m 2 ·24h·0.1MPa).

[0130] Heat sealing strength: 41N / 15mm.

[0131] Tensile strength: 39.5MPa in longitudinal direction, 38.5MPa in transverse direction.

[0132] Elongation at break: 702% longitudinally, 585% transversely.

[0133] There was no leakage or damage during pressurization.

[0134] After being frozen at zero degrees for 48 hours, it dropped from 2 meters without any leakage or damage.

[0135] Comparative Example 1

[0136] This comparative example is modified as follows based on Example 2:

[0137] The middle layer is composed of the following raw materials in parts by weight: 29 parts of linear polyethylene, 15 parts of SEBS, 55 parts of high-density polyethylene, and 1 part of cross-linked modified polyethylene.

[0138] The performance test was carried out according to the multi-layer co-extrusion infusion film standard in the YBB standard, and the results are as follows:

[0139] Water vapor transmission rate: 1.7g / (m 2 ·24h).

[0140] Oxygen permeability: 852.42cm 3 / (m 2 ·24h·0.1MPa).

[0141] Heat sealing strength: 41.4N / 15mm.

[0142] Tensile strength: 38MPa in longitudinal direction, 37MPa in transverse direction.

[0143] Elongation at break: 636% in longitudinal direction, 519% in transverse direction.

[0144] There was no leakage or damage during pressurization.

[0145] After being frozen at zero degrees for 48 hours, it dropped from 2 meters without any leakage or damage.

[0146] Comparative Example 2

[0147] This comparative example is modified as follows based on Example 2:

[0148] The middle layer is composed of the following raw materials in parts by weight: 30 parts of linear polyethylene, 15 parts of SEBS, and 55 parts of high-density polyethylene.

[0149] The performance test was carried out according to the multi-layer co-extrusion infusion film standard in the YBB standard, and the results are as follows:

[0150] Water vapor transmission rate: 1.66g / (m 2 ·24h).

[0151] Oxygen permeability: 849.39cm 3 / (m 2 ·24h·0.1MPa).

[0152] Heat sealing strength: 41.0N / 15mm.

[0153] Tensile strength: 37MPa in longitudinal direction, 36MPa in transverse direction.

[0154] Elongation at break: 539% longitudinally, 443% transversely.

[0155] There was no leakage or damage during pressurization.

[0156] After being frozen at zero degrees for 48 hours, it dropped 2 meters and showed slight leakage and damage.

[0157] Comparative Example 3

[0158] This comparative example is modified as follows based on Example 2:

[0159] The cross-linked modified polyethylene is composed of the following raw materials in parts by weight: 94 parts of linear polyethylene, 5 parts of vinyl trimethoxy silane, 0.25 parts of dibenzoyl peroxide, 0.10 parts of dibutyltin dilaurate, and 0.65 parts of hindered phenol antioxidant.

[0160] The performance test was carried out according to the multi-layer co-extrusion infusion film standard in the YBB standard, and the results are as follows:

[0161] Water vapor transmission rate: 1.69g / (m 2 ·24h).

[0162] Oxygen permeability: 851.22cm 3 / (m 2 ·24h·0.1MPa).

[0163] Heat sealing strength: 41.5N / 15mm.

[0164] Tensile strength: 37.9MPa in longitudinal direction, 36.7MPa in transverse direction.

[0165] Elongation at break: 611% in longitudinal direction, 500% in transverse direction.

[0166] There was no leakage or damage during pressurization.

[0167] After being frozen at zero degrees for 48 hours, it dropped from 2 meters without any leakage or damage.

[0168] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A three-layer infusion film with low temperature resistance and high toughness, characterized in that: From the inside to the outside, it includes the inner layer, the middle layer and the outer layer; among them, The inner layer is composed of the following raw materials in parts by weight: 30-40 parts of metallocene polyethylene, 5-15 parts of ultra-low density polyethylene, and 50-60 parts of high-density polyethylene; The middle layer is composed of the following raw materials in parts by weight: 25-30 parts of linear polyethylene, 10-15 parts of hydrogenated styrene-butadiene block copolymer, 40-60 parts of high-density polyethylene, and 2-10 parts of cross-linked modified polyethylene; The outer layer is composed of the following raw materials in parts by weight: 20-40 parts of linear polyethylene, 5-15 parts of ultra-low density polyethylene, and 55-65 parts of high-density polyethylene.

2. The low-temperature-resistant and high-toughness three-layer infusion film according to claim 1, characterized in that: The thickness of the inner layer is 30-40um, the thickness of the middle layer is 140-150um, and the thickness of the outer layer is 30-40um.

3. The low-temperature-resistant and high-toughness three-layer infusion film according to claim 1, characterized in that: The metallocene polyethylene used in the inner layer has a melting point of 110-130°C and a density of 0.92-0.95 g / cm 3 , a melt index of 0.5-1.5 g / 10 min; and / or, The ultra-low density polyethylene used in the inner layer has a melting point of 110-120°C and a density of 0.89-0.92 g / cm 3 , a melt index of 0.2-0.8 g / 10 min; and / or, The high-density polyethylene used in the inner layer has a melting point of 120-140°C and a density of 0.94-0.97 g / cm 3 , the melt index is 0.4-0.8g / 10min.

4. The low-temperature-resistant and high-toughness three-layer infusion film according to claim 1, characterized in that: The linear polyethylene used in the middle layer has a melting point of 105-120°C and a density of 0.9-0.95 g / cm 3 , a melt index of 1.5-2.5 g / 10 min; and / or, The density of the hydrogenated styrene-butadiene block copolymer used in the middle layer is 0.9-0.95 g / cm 3 , a melt index of 2.0-3.5 g / 10 min; and / or, The high-density polyethylene used in the middle layer has a melting point of 120-140°C and a density of 0.94-0.97 g / cm 3 , the melt index is 0.4-0.8g / 10min.

5. The low-temperature-resistant and high-toughness three-layer infusion film according to claim 1, characterized in that: The linear polyethylene used in the outer layer has a melting point of 105-120°C and a density of 0.9-0.95 g / cm 3 , a melt index of 1.5-2.5 g / 10 min; and / or, The ultra-low density polyethylene used in the outer layer has a melting point of 110-120°C and a density of 0.89-0.92 g / cm 3 , a melt index of 0.2-0.8 g / 10 min; and / or, The high-density polyethylene used in the outer layer has a melting point of 120-140°C and a density of 0.94-0.97 g / cm 3 , the melt index is 0.4-0.8g / 10min.

6. The low-temperature-resistant and high-toughness three-layer infusion film according to claim 1, characterized in that: The cross-linked modified polyethylene is composed of the following raw materials in parts by weight: 80-98 parts of linear polyethylene, 1-10 parts of vinyl trimethoxy silane, 0.05-0.5 parts of dibenzoyl peroxide, 0.02-0.15 parts of dibutyltin dilaurate, 0-1 parts of hindered phenol antioxidants, and 1-5 parts of nano calcium carbonate.

7. A method for preparing the low-temperature-resistant and high-toughness three-layer infusion film according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, blending and granulating the metallocene polyethylene, ultra-low density polyethylene and high-density polyethylene to obtain inner layer pellets; S2, blending and granulating the linear polyethylene, hydrogenated styrene-butadiene block copolymer, high-density polyethylene and cross-linked modified polyethylene to obtain middle-layer pellets; S3, blending and granulating the linear polyethylene, ultra-low density polyethylene and high-density polyethylene to obtain outer layer pellets; S4, using a bottom-blowing water-cooled three-layer co-extrusion film blowing machine for processing, and heating the inner layer, middle layer and outer layer host; S5, adding the pellets of each layer into the corresponding main machine hopper respectively, and carrying out film blowing production to obtain the three-layer infusion film.

8. The method for preparing the low-temperature-resistant and high-toughness three-layer infusion film according to claim 7, characterized in that: The temperature of the inner layer main engine is 160-210°C, the temperature of the middle layer main engine is 160-210°C, the temperature of the outer layer main engine is 160-210°C, and the temperature of the die head is 170-190°C.

9. The method for preparing the low-temperature-resistant and high-toughness three-layer infusion film according to claim 7, characterized in that: In step S2, the method for preparing the cross-linked modified polyethylene comprises: ss1: linear polyethylene, vinyl trimethoxysilane, dibenzoyl peroxide, dibutyltin dilaurate, hindered phenol antioxidant and nano calcium carbonate are mixed to obtain a mixture; ss2 melt-extrudes the mixture and controls the temperature of the melt-extruded material to carry out a cross-linking reaction to obtain a cross-linked modified polyethylene.

10. The method for preparing the low-temperature-resistant and high-toughness three-layer infusion film according to claim 9, characterized in that: In step ss2, the temperature of the melt extrusion is 180-220°C.

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