Low-temperature unblocking high-temperature resistant water-blocking PE film and preparation method thereof

Abstract

This application relates to the field of polymer materials, specifically disclosing a low-temperature sealing, high-temperature-resistant, and water-blocking PE film and its preparation method. The low-temperature sealing, high-temperature-resistant, and water-blocking PE film comprises, from the inside out, an inner layer, a sub-inner layer, a middle layer, a sub-outer layer, and an outer layer. The inner layer comprises the following raw materials: LDPE, LLDPE, MLLDPE, PPA additives, slip agent, and opening agent; the sub-inner layer comprises the following raw materials: HDPE, barrier masterbatch, and PPA additives; the middle layer comprises the following raw materials: HDPE, barrier masterbatch, and PPA additives; the sub-outer layer comprises the following raw materials: HDPE, barrier masterbatch, and PPA additives; and the outer layer comprises the following raw materials: LLDPE, MLLDPE, HDPE, barrier masterbatch, PPA additives, and antioxidants. The PE film of this application is made of a single material, is easy to recycle, has good water and oxygen barrier properties, strong temperature resistance, low thermal shrinkage, low sealing temperature, and high heat-sealing strength.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, and more specifically, it relates to a low-temperature sealing, high-temperature resistant, water-blocking PE film and its preparation method. Background Technology

[0002] In recent years, plastic packaging materials have mainly developed towards high barrier properties, non-toxicity, anti-aging properties, high strength, co-extruded films, composite films, and environmental friendliness. Polyethylene (PE) is the simplest structural high-molecular organic compound and one of the most widely used polymer materials in the world today. Raw materials are molded through blending, injection molding, extrusion, and blow molding, and it is widely used in industrial and agricultural packaging, food packaging, and daily life. PE is a polymer synthesized from ethylene monomers and is a typical thermoplastic. It is an odorless, tasteless, non-toxic, flammable white powder. Factors such as the crystallinity and relative molecular mass of PE have a certain influence on its physical and mechanical properties. It has excellent mechanical properties, good water vapor barrier properties, high impact strength, light weight, and good printability. However, PE materials also have shortcomings; its oxygen barrier properties are poor, and it cannot effectively prevent oxygen from permeating through the external environment. Therefore, research on how to improve the barrier properties of PE films is currently a key focus in the field of PE film technology.

[0003] Currently, to improve the barrier properties of PE films, composite structures are often used, such as PET / PE, BOPP / PE, PA / PE, KPET / PE, or three-layer structures like PET / PA / PE and BOPP / PA / PE. PE composite films using multiple materials are cumbersome and difficult to sort and classify during recycling, resulting in low recycling rates. Influenced by environmental policies and the concept of sustainable development, the use of single-material plastic packaging is increasingly valued. Using single materials as much as possible while ensuring packaging performance requirements to facilitate recycling has become a consensus for healthy industry development. However, single-material PE films often use a PE / PE structure, with both layers being ordinary polyethylene resin, which cannot meet the moisture and oxygen barrier requirements of high-quality products. Summary of the Invention

[0004] In order to improve the water and oxygen barrier properties of polyethylene and meet the recycling requirements of a single material, this application provides a low-temperature sealing high-temperature resistant water-barrier PE film and its preparation method.

[0005] In the first aspect, this application provides a low-temperature sealing high-temperature resistant and water-resistant PE film, which adopts the following technical solution: a low-temperature sealing high-temperature resistant and water-resistant PE film, comprising the following five layers from the inside to the outside: inner layer, second inner layer, middle layer, second outer layer and outer layer;

[0006] The inner layer comprises the following raw materials in parts by weight: 8-12 parts LDPE, 25-35 parts LLDPE, 55-65 parts MLLDPE, 0.6-1 parts PPA additive, 1.2-2 parts slip agent, and 5-6 parts opening agent;

[0007] The innermost layer comprises the following raw materials in parts by weight: 90-100 parts HDPE, 1-2 parts barrier masterbatch, and 0.2-0.6 parts PPA additive; the middle layer comprises the following raw materials in parts by weight: 90-100 parts HDPE, 2.5-3.5 parts barrier masterbatch, and 0.2-0.6 parts PPA additive.

[0008] The secondary outer layer comprises the following raw materials in parts by weight: 90-100 parts HDPE, 2-3 parts barrier masterbatch, and 0.2-0.6 parts PPA additive; the outer layer comprises the following raw materials in parts by weight: 35-45 parts LLDPE, 25-35 parts MLLDPE, 25-35 parts HDPE, 3.5-4 parts barrier masterbatch, 0.2-0.6 parts PPA additive, and 0.2-0.6 parts antioxidant.

[0009] By adopting the above technical solution, the inner layer raw materials use low-density polyethylene, linear low-density polyethylene, and metallocene linear low-density polyethylene, mixed in a certain proportion. This reduces the inner layer density while lowering the heat-sealing temperature, thus improving heat-sealing performance. It also reduces bag-making temperature and pressure, minimizing heat-sealing damage to the PE film and providing better barrier properties. Furthermore, the addition of opening agents, slip agents, and PPA additives improves antistatic and lubricity properties, enhances moisture resistance, significantly reduces the coefficient of friction and adhesion resistance, and substantially improves... High blown film efficiency prevents film adhesion and granule agglomeration, increases film surface smoothness, and reduces dust accumulation. The amount of barrier masterbatch is set from the outside to the inside in the inner, outer, middle, and outer layers, thus achieving a zigzag pulse effect and improving the film's gas barrier properties. Moreover, HDPE is added to the inner, middle, outer, and outer layers to increase the density of the PE film itself, improve the overall temperature resistance and barrier properties, and reduce the permeability of water vapor and oxygen.

[0010] Optionally, the inner layer comprises MLLDPE with a mass ratio of 1:1.5-2 and a density of 0.915 g / cm³. 3 MLLDPE of grade I with a melt index of 1 g / 10 min and a density of 0.913 g / cm³ 3 MLLDPE of type II with a melt index of 2 g / 10 min.

[0011] By adopting the above technical solution, the inner layer uses two materials with similar densities, both below 0.915 g / cm³. 3MLLDPE has a narrower molecular weight distribution, higher copolymer content and more uniform polymer structure, resulting in lower initial sealing strength and stronger heat sealing strength, while improving the film's tear resistance and puncture resistance.

[0012] Optionally, the HDPE in the innermost layer comprises a mass ratio of 1:1.5-2 with a density of 0.969 g / cm³. 3 HDPE No. 1 with a melt index of 1.2 g / 10 min and a density of 0.950 g / cm³ 3 HDPE No. 2 with a melt index of 0.9 g / 10 min;

[0013] The intermediate layer contains HDPE with a mass ratio of 1:1.5-2 and a density of 0.969 g / cm³. 3 HDPE No. 1 with a melt index of 1.2 g / 10 min and a density of 0.956 g / cm³ 3 HDPE No. 3 with a density of 1g / 10min;

[0014] The outermost layer contains HDPE with a mass ratio of 1:1.5-2 and a density of 0.969 g / cm³. 3 HDPE No. 1 with a melt index of 1.2 g / 10 min and a density of 0.958 g / cm³ 3 , No. 4 HDPE with a density of 0.28 g / 10 min.

[0015] By adopting the above technical solution, two types of HDPE based on HDPE No. 2 are added to the innermost layer, middle layer, and outermost layer, with the densities of the two HDPEs ranging from 0.95 to 0.97 g / cm³. 3 Between these elements, the overall density of the PE film is increased, improving its temperature resistance and barrier properties, reducing heat shrinkage, and enhancing its resistance to boiling.

[0016] Optionally, the density of LLDPE in the outer layer is 0.9188 g / cm³. 3 The melt flow index is 1.9 g / 10 min, and the density of MLLDPE is 0.94 g / cm³. 3 The melt flow index is 0.9 g / 10 min, and the density of HDPE is 0.961 g / cm³. 3 The melt flow index is 0.7 g / 10 min.

[0017] By adopting the above technical solution, the density of HDPE in the outer layer is higher than that of HDPE No. 2, HDPE No. 3, and HDPE No. 4 in the inner, middle, and outer layers, which can provide better barrier properties. At the same time, it can improve the tear resistance and impact resistance of the PE film. Moreover, HDPE and MLLDPE in the outer layer can work together to control the crystallinity and melting point of the outer layer, thereby improving the barrier properties and heat resistance of the PE film and reducing gas permeation.

[0018] Optionally, the density of LDPE in the inner layer is 0.924 g / cm³. 3 The melt flow index is 1.9 g / 10 min, and the density of LLDPE is 0.918 g / cm³. 3 The melt flow index is 2 g / 10 min.

[0019] By adopting the above technical solutions, both LDPE and LLDPE are low-density polyethylenes. LLDPE has the characteristics of high impact resistance and good creep resistance at high temperature, while LDPE has good flexibility, transparency and elongation, which can reduce the density of the inner layer and improve barrier properties.

[0020] Optionally, the barrier masterbatch is prepared as follows:

[0021] Oxidized cellulose nanofibers were ultrasonically dispersed in deionized water for 1-2 hours to prepare a suspension with a concentration of 0.5-1 wt%. Polyvinyl alcohol was dissolved in deionized water to prepare a polyvinyl alcohol aqueous solution with a concentration of 3.5-4 wt%. Aramid fibers were broken into 3-5 mm fragments, added to ethanol, ultrasonically removed impurities, and then dissolved to prepare a dispersion with a concentration of 0.5-0.7 wt%.

[0022] A polyvinyl alcohol aqueous solution and a suspension were mixed, stirred evenly, degassed, cast, and dried to obtain a matrix film. The mass ratio of oxidized nanocellulose filaments to polyvinyl alcohol was 1-1.5:1.

[0023] The matrix membrane is immersed and pulled in the dispersion 3-5 times, then immersed in a tert-butanol solution with a concentration of 50-55wt% at 60-70℃ for 1-3 minutes. It is then removed, washed repeatedly with ultrapure water and anhydrous ethanol, freeze-dried, and pulverized to obtain the initial powder. The initial powder and HDPE No. 1 are mixed, melted, and granulated at a mass ratio of 0.03-0.06:1.

[0024] By employing the above technical solution, the oxidized cellulose nanofibers are TEMPO-oxidized cellulose nanofibers containing a large number of free hydroxyl and carboxyl groups. Polyvinyl alcohol, as a long-chain semi-crystalline polymer, has abundant hydroxyl sites in its aqueous solution. Therefore, the oxidized cellulose nanofibers and polyvinyl alcohol can form multiple hydrogen bonds. This hydrogen bonding reduces the content of free hydroxyl groups in the molecular chains of both, lowers the surface energy of the matrix film, inhibits the formation of hydrogen bonds with water droplets, and improves water resistance. Then, a dispersion formed from aramid fibers is freeze-dried on the matrix film to form an aerogel. Due to the highly oriented molecular chains of aramid fibers, they possess extremely strong intermolecular forces, giving them chemical stability. The strong properties of the aramid nanofibers were obtained by dissolving them in a mixture of potassium hydroxide and dimethyl sulfoxide. After impregnation, the aramid nanofibers were deposited on the substrate film and freeze-dried to form aggregates with a layered three-dimensional network structure on the substrate film. These aggregates have a large number of mesoporous structures, which prolongs the permeation path of water vapor and oxygen, improving the barrier properties. They also have good flexibility and excellent UV protection, thus improving the tensile strength of the PE film. Finally, HDPE No. 1, which is contained in the inner, middle and outer layers, was used as the base material for the barrier masterbatch. This increased the dispersibility and compatibility of the barrier masterbatch in the inner, middle and outer layers, and reduced the impact of the barrier masterbatch on the mechanical strength of the PE film.

[0025] Optionally, the dispersion may also contain glyceryl tristearate-modified silica, wherein the mass ratio of glyceryl tristearate-modified silica to aramid fibers in the dispersion is 0.1-0.2:1.

[0026] By adopting the above technical solution, aramid fiber is made of aromatic polyamide, which contains polar amide groups in its molecular structure, so it has a certain polarity. When it is mixed and melted with No. 1 HDPE, in order to improve the dispersion uniformity of it with No. 1 HDPE, tristearate-modified silica is added to the dispersion to increase its hydrophobicity, thereby making the surface of the barrier masterbatch hydrophobic, increasing its dispersibility in No. 1 HDPE, and reducing the dispersion and dissolution of water vapor in aramid aerogel, making it difficult for water vapor to diffuse inward through the barrier masterbatch. Moreover, it reduces the porosity of aramid aerogel, reduces light scattering and refraction, and increases the transparency of the film.

[0027] Optionally, the thickness ratio of the inner layer, the second inner layer, the middle layer, the second outer layer, and the outer layer is 2-2.5:1-1.5:2.8-3:1-1.5:2-2.5.

[0028] By adopting the above technical solution and adjusting the thickness ratio between each layer, better gas and moisture barrier performance can be provided, enhancing the preservation and protection effect of PE film. Moreover, the inner layer can directly improve the heat sealing strength and heat sealing uniformity, while the outer layer can increase the mechanical strength and stiffness of PE film and improve barrier strength.

[0029] Secondly, this application provides a method for preparing a low-temperature sealing, high-temperature resistant, water-blocking PE film, using the following technical solution:

[0030] A method for preparing a low-temperature sealing, high-temperature resistant, water-blocking PE film includes the following steps:

[0031] The raw materials in the inner layer, the second inner layer, the middle layer, the second outer layer, and the outer layer are mixed evenly to obtain the inner layer material, the second outer layer material, the middle layer material, the second outer layer material, and the outer layer material.

[0032] The inner layer material, the second outer layer material, the middle layer material, the second outer layer material, and the outer layer material are added into the hopper of the extruder, and then extruded, melted, cast, drawn, blown, pulled, and wound to produce a PE film.

[0033] By adopting the above technical solution, the raw materials of each layer are first mixed evenly separately, and then extruded and blown using a five-layer co-extrusion equipment. The film bubble is stable and not prone to wrinkles or folds. The finished product has a high qualification rate and is more suitable for actual industrial production. The blown film has excellent stability, so the film can have the advantages of good blown film processing, high toughness and high strength at the same time. It can withstand high-temperature cooking and is not prone to thermal expansion and bag breakage.

[0034] Optionally, the traction speed is 15-20 m / min and the inflation ratio is 2-3:1.

[0035] By adopting the above technical solution, controlling the traction speed during inflation can prevent defects or ruptures on the surface of the membrane bubble, reduce the impact on the mechanical strength of the PE film, and improve the thickness, transparency, and strength of the PE film.

[0036] In summary, this application has the following beneficial effects:

[0037] 1. Since this application uses five layers of co-extrusion to prepare PE film, and all of them are of a single material, they are easy to recycle. The inner layer is made of low-density LDPE, LLDPE and MLLDPE, which can reduce the density of the inner layer as much as possible, thereby reducing the initial sealing temperature, improving the heat sealing effect, reducing the damage of heat sealing to PE film, and improving barrier properties. Moreover, the amount of barrier masterbatch added from the outside to the inside is set in the order of high-low-high-low, which can play a zigzag pulse effect and maximize the barrier properties of PE film.

[0038] 2. In this application, two MLLDPE seat inner layer materials with different densities and melt indexes are preferably used to further reduce the density of the inner layer from the raw material, increase heat sealing performance, and improve tear resistance and puncture resistance.

[0039] 3. In this application, oxidized cellulose nanofibers, polyvinyl alcohol, and aramid fibers are preferred to prepare the barrier masterbatch. Oxidized cellulose nanofibers and polyvinyl alcohol can form a hydrophobic matrix film through multiple hydrogen bonding. The dispersion formed by aramid fibers can be freeze-dried on the matrix film to form an aerogel, thereby extending the gas permeation path and improving the barrier ability against water vapor and oxygen. Detailed Implementation

[0040] The following embodiments provide a further detailed description of this application.

[0041] Example I-1 of the preparation of tristearate modified silica: Nano silica was dried at 60℃ for 24h. 300mL of anhydrous ethanol and 100mL of deionized water were mixed evenly, and 4g of dried nano silica was added. The mixture was ultrasonically dispersed for 2h. 0.8g of silicon coupling agent KH570 was taken and hydrolyzed with 10mL of anhydrous ethanol and 10mL of acetic acid solution with pH 3 (diluted with glacial acetic acid) for 1h. The hydrolysate was added to the ultrasonically dispersed nano silica and stirred in a constant temperature water bath at 75℃ for 4h. The mixture was centrifuged at 8000r / min for 10min and the precipitate was vacuum dried at 80℃ for 48h.

[0042] Preparation Examples of Barrier Masterbatch 1-4

[0043] Preparation Example 1: 35g of TEMPO-oxidized cellulose nanofibers were added to deionized water and ultrasonically dispersed at 60W for 2 hours to prepare a suspension with a concentration of 0.5wt%. 35g of polyvinyl alcohol was added to deionized water and stirred at 90℃ for 1 hour. After cooling and degassing, a polyvinyl alcohol aqueous solution with a concentration of 3.5wt% was prepared. Aramid fibers were broken into 5mm fragments and added to ethanol. The mixture was ultrasonically removed at 50W for 30 minutes. 20g of the removed aramid fibers were then added to DMSO / H2O (volume ratio 25:1). Then add 30g of potassium hydroxide and mechanically stir at 800r / min for 8h to obtain a dispersion with a concentration of 0.7wt%. Add tristearate-modified silica to the dispersion. The mass ratio of aramid fiber to tristearate-modified silica is 1:0.2. The tristearate-modified silica is prepared by Preparation Example I-1. TEMPO oxidized cellulose nanofibers are selected from Zhejiang Jinjiahao Green Nanoparticles, item number 009. The fineness of the aramid fiber is 400D. The polyvinyl alcohol is PVA1799.

[0044] The polyvinyl alcohol aqueous solution and suspension were mixed and stirred at 800 r / min for 3 h at 50 °C. The mixture was then degassed under vacuum, cast into a film, dried at room temperature for 24 h, dried at 45 °C for 48 h, and then dried at 60 °C for 48 h. The film thickness was 5 μm.

[0045] The substrate membrane was immersed and stretched 5 times in the dispersion, then immersed in a 50 wt% tert-butanol solution at 60°C for 3 min. The substrate membrane was removed, washed repeatedly with ultrapure water and anhydrous ethanol 5 times, frozen to -70°C, then freeze-dried and pulverized to obtain the initial powder.

[0046] The initial powder and HDPE No. 1 were mixed at a mass ratio of 0.06:1, melted, extruded, and granulated at 150℃. The density of HDPE No. 1 was 0.969 g / cm³. 3 The melt flow index is 1.2 g / 10 min, and it is selected from Dow Chemical, USA, model AT6900.

[0047] Preparation Example 2: 60g of TEMPO-oxidized cellulose nanofibers were added to deionized water and ultrasonically dispersed at 60W for 1h to prepare a 1wt% suspension. 40g of polyvinyl alcohol was added to deionized water and stirred at 90℃ for 1h. After cooling and degassing, a 4wt% polyvinyl alcohol aqueous solution was prepared. Aramid fibers were broken into 3mm fragments and added to ethanol. Impurities were removed by ultrasonication at 50W for 30min. 20g of the removed aramid fibers were added to DMSO / H2O (volume ratio 25:1) and then... 30g of potassium hydroxide was mechanically stirred at 800r / min for 8h to obtain a dispersion with a concentration of 0.5wt%. Tristearate-modified silica was added to the dispersion. The ratio of tristearate-modified silica to aramid fibers in the dispersion was 0.2:1. The tristearate-modified silica was prepared by Preparation Example I-1. TEMPO oxidized cellulose nanofibers were selected from Zhejiang Jinjiahao Green Nanoparticles, catalog number 009. The aramid fiber fineness was 400D. The polyvinyl alcohol was PVA1799.

[0048] The polyvinyl alcohol aqueous solution and suspension were mixed and stirred at 800 r / min for 3 h at 50 °C. The mixture was then degassed under vacuum, cast into a film, dried at room temperature for 24 h, dried at 45 °C for 48 h, and then dried at 60 °C for 48 h. The film thickness was 5 μm.

[0049] The substrate membrane was immersed and stretched three times in the dispersion, and then immersed in a 55 wt% tert-butanol solution at 70°C for 1 min. The substrate membrane was then removed, washed three times with ultrapure water and anhydrous ethanol, frozen to -70°C, freeze-dried, and pulverized to obtain the initial powder.

[0050] The initial powder and HDPE No. 1 were mixed at a mass ratio of 0.03:1, melted, extruded, and granulated at 150℃. The density of HDPE No. 1 was 0.969 g / cm³. 3 The melt flow index is 1.2 g / 10 min, and it is selected from Dow Chemical, USA, model AT6900.

[0051] Preparation Example 3: The difference from Preparation Example 1 is that glyceryl tristearate-modified silica was not added to the dispersion.

[0052] Preparation Example 4: 35g of TEMPO-oxidized cellulose nanofibers were added to deionized water and ultrasonically dispersed at 60W for 2h to prepare a suspension with a concentration of 0.5wt%. 35g of polyvinyl alcohol was added to deionized water and stirred at 90℃ for 1h. After cooling and degassing, a polyvinyl alcohol aqueous solution with a concentration of 3.5wt% was prepared. Aramid fibers were broken into 5mm fragments and added to ethanol. The mixture was ultrasonically removed at 50W for 30min. 20g of the removed aramid fibers were added to DMSO / H2O (volume ratio of 25:1) and 30g of potassium hydroxide were added. The mixture was mechanically stirred at 800r / min for 8h to obtain a dispersion with a concentration of 0.7wt%. The TEMPO-oxidized cellulose nanofibers were selected from Zhejiang Jinjiahao Green Nanoparticles, item number 009. The fineness of the aramid fibers was 400D, and the polyvinyl alcohol was PVA1799.

[0053] The polyvinyl alcohol aqueous solution and suspension were mixed and stirred at 800 r / min for 3 h at 50 °C. The mixture was then degassed under vacuum, cast into a film, dried at room temperature for 24 h, dried at 45 °C for 48 h, and then dried at 60 °C for 48 h. The film thickness was 5 μm. The film was then pulverized to prepare the initial powder.

[0054] The initial powder and HDPE No. 1 were mixed at a mass ratio of 0.06:1, melted, extruded, and granulated at 150℃. The density of HDPE No. 1 was 0.969 g / cm³. 3 The melt flow index is 1.2 g / 10 min, and it is selected from Dow Chemical, USA, model AT6900.

[0055] Example

[0056] Example 1: A low-temperature sealing, high-temperature resistant, water-blocking PE film, comprising, from the inside out, an inner layer, a second inner layer, a middle layer, a second outer layer, and an outer layer. The thickness ratio of the inner layer, second inner layer, middle layer, second outer layer, and outer layer is 2:1:3:1:2. The raw material usage for each layer is shown in Table 1. The melt index of LDPE in the inner layer is 1.9 g / 10 min, and the density is 0.924 g / cm³. 3 The raw material is selected from CNOOC Shell, model number 2420; the LLDPE is selected from Kuwait Equate, model number 7050, with a density of 0.918 g / cm³. 3 The melt flow index is 2 g / 10 min. MLLDPE includes MLLDPE No. I and MLLDPE No. II with a mass ratio of 1:2. The density of MLLDPE No. I is 0.915 g / cm³. 3The melt flow index is 1 g / 10 min, it is selected from Repman Japan, model SP0820, and the density of No. II MLLDPE is 0.913 g / cm³. 3 The melt flow index is 2 g / 10 min, it is selected from Mitsui Metallocene, model SP1520, the opening agent is oleamide, and the lubricant is ethylene bisoleamide;

[0057] The innermost layer contains HDPE of type 1 and type 2 in a mass ratio of 1:1.5, with type 1 HDPE having a density of 0.969 g / cm³. 3 The melt index is 1.2 g / 10 min, selected from Dow Chemical, USA, model AT6900; the density of No. 2 HDPE is 0.95 g / cm3, melt index is 0.9 g / 10 min, selected from Yanshan Petrochemical, model 5000S;

[0058] The intermediate layer of HDPE consists of HDPE No. 1 and HDPE No. 3 in a mass ratio of 1:1.5, with HDPE No. 1 having a density of 0.969 g / cm³. 3 The melt flow index is 1.2 g / 10 min, it is selected from Dow Chemical, USA, and the density of HDPE No. 3 is 0.956 g / cm³. 3 The density is 1g / 10min, and it is sourced from Total Korea, model F920A.

[0059] The outermost layer contains HDPE of type 1 and type 4 in a mass ratio of 1:1.5, with type 1 HDPE having a density of 0.969 g / cm³. 3 The melt flow index is 1.2 g / 10 min, and it is sourced from Dow Chemical Company, USA. The viscosity of HDPE No. 4 is 0.958 g / cm³. 3 The melt flow index is 0.28 g / 10 min, and it is sourced from DowDuPont, USA, model DMDB-6200T;

[0060] The outer layer contains LLDPE with a density of 0.9188 g / cm³, a melt flow index of 1.9 g / 10 min, sourced from Lanzhou Petrochemical, grade 7042N, and an MLLDPE density of 0.94 g / cm³. 3 The melt flow index is 0.9 g / 10 min, it is selected from Exxon Chemical 4009MA, and the HDPE density is 0.961 g / cm³. 3 The melt index is 0.7 g / 10 min, it is selected from Exxon Chemicals, model HTA108, and the antioxidant is antioxidant 1010;

[0061] The barrier masterbatch in the inner, middle, outer, and outer layers is selected from Dongguan Ruiyi Polymer Materials, model PE9413, and the PPA additives in the five layers are all selected from DuPont Z200.

[0062] The preparation method of the above-mentioned low-temperature sealing high-temperature resistant water-blocking PE film includes the following steps;

[0063] The raw materials in the inner layer, the second inner layer, the middle layer, the second outer layer, and the outer layer are mixed evenly to obtain the inner layer material, the second outer layer material, the middle layer material, the second outer layer material, and the outer layer material.

[0064] The inner layer material, the second outer layer material, the middle layer material, the second outer layer material, and the outer layer material are added into the hopper of the extruder accordingly. After extrusion and melting, the temperatures of each zone in the inner layer extruder are: Zone 1 150℃, Zone 2 150℃, Zone 3 155℃, Zone 4 160℃, Zone 5 160℃, and Zone 6 155℃. The rotation speed of the inner layer extruder is 65 r / min. The temperatures of each zone in the second inner layer extruder are: Zone 1 155℃, Zone 2 155℃, Zone 3 160℃, Zone 4 160℃, Zone 5 160℃, and Zone 6 155℃. The temperatures of the extruder zones are as follows: 0℃, 165℃ in zone 4, 165℃ in zone 5, and 160℃ in zone 6. The speed of the main extruder in the innermost layer is 70 rpm. The temperatures of the extruder zones in the middle layer are: 160℃ in zone 1, 160℃ in zone 2, 165℃ in zone 3, 170℃ in zone 4, 170℃ in zone 5, and 165℃ in zone 6. The speed of the main extruder in the middle layer is 70 rpm. The temperatures of the extruder in the outermost layer are: 155℃ in zone 1, 155℃ in zone 2, and 160℃ in zone 3. The temperatures in each zone of the outer extruder are: 165℃ in zone four, 165℃ in zone five, and 160℃ in zone six. The outer extruder's main machine speed is 70 r / min. The temperatures in each zone of the outer extruder are: 155℃ in zone one, 155℃ in zone two, 160℃ in zone three, 160℃ in zone four, 160℃ in zone five, and 155℃ in zone six. The inner extruder's main machine speed is 65 r / min. Then, the extrusion blow molding is performed under an air pressure of 1.5 MPa, with the blow-up ratio controlled at 3:1. The internal cooling air intake frequency of the rotary air shaft cooler is 20 Hz, and the internal cooling air exhaust frequency is 25 Hz. The molten plastic is pulled upward and quickly kneaded at a traction speed of 20 m / min. Compressed air is then injected into the die head air inlet, with the blow-up ratio controlled at 3:1. The film bubble is then pulled up at a uniform speed by a traction rope. The film bubble is then pulled into the corona machine by guide rollers. The corona machine discharge power is 6A. After passing through the correction clamps, it enters the winding roller machine to obtain a PE film with a thickness of 60 μm.

[0065] Table 1. Raw material consumption for low-temperature sealing high-temperature resistant and water-blocking PE films in Examples 1-7

[0066]

[0067]

[0068] Example 2-3: A low-temperature sealing high temperature resistance and water-blocking PE film, which differs from Example 1 in that the raw material usage of the inner layer, the second inner layer, the middle layer, the second outer layer, and the outer layer is as shown in Table 1, and the thickness ratio of the inner layer, the second inner layer, the middle layer, the second outer layer, and the outer layer is 2.5:1.5:2.8:1.5:2.5.

[0069] Example 4: A low-temperature sealing high-temperature resistant and water-resistant PE film, which differs from Example 1 in that the raw material dosage is as shown in Table 1, and No. II MLLDPE is used instead of No. I MLLDPE in the inner layer.

[0070] Example 5: A low-temperature sealing high-temperature resistant and water-resistant PE film, which differs from Example 1 in that the raw material dosage is as shown in Table 1, and No. I MLLDPE is used instead of No. II MLLDPE in the inner layer.

[0071] Example 6: A low-temperature sealing high-temperature resistant and water-blocking PE film, which differs from Example 1 in that the raw material usage is as shown in Table 1, and in the innermost layer, middle layer and outermost layer, HDPE No. 1 is used instead of HDPE No. 2.

[0072] Example 7: A low-temperature sealing high-temperature resistant and water-blocking PE film, which differs from Example 1 in that the raw material dosage is as shown in Table 1. In the inner layer, middle layer and outer layer, only HDPE No. 1 is added, and HDPE No. 2 is not added.

[0073] Example 8: A low-temperature sealing high-temperature resistant water-blocking PE film, which differs from Example 1 in that the barrier masterbatch in the inner layer, middle layer, outer layer and outer layer is made from Preparation Example 1.

[0074] Example 9: A low-temperature sealing high-temperature resistant water-blocking PE film, which differs from Example 1 in that the barrier masterbatch in the inner layer, middle layer, outer layer and outer layer is made from Preparation Example 2.

[0075] Example 10: A low-temperature sealing high-temperature resistant water-blocking PE film, which differs from Example 1 in that the barrier masterbatch in the inner layer, middle layer, outer layer and outer layer is made from Preparation Example 3.

[0076] Example 11: A low-temperature sealing high-temperature resistant water-blocking PE film, which differs from Example 1 in that the barrier masterbatch in the inner layer, middle layer, outer layer and outer layer is made from Preparation Example 4.

[0077] Comparative Example

[0078] Comparative Example 1: A low-temperature sealing high-temperature resistant and water-blocking PE film, which differs from Example 1 in that the raw material dosage is as shown in Table 2, and no MLLDPE is added to the inner layer.

[0079] Comparative Example 2: A low-temperature sealing high-temperature resistant water-blocking PE film, which differs from Example 1 in that the raw material dosage is shown in Table 2, and no barrier masterbatch is added to the inner, middle and outer layers.

[0080] Comparative Example 3: A low-temperature sealing high-temperature resistant water-blocking PE film, which differs from Example 1 in that the raw material dosage is as shown in Table 2, and the amount of barrier masterbatch added in the inner layer, middle layer and outer layer is adjusted to 3 kg.

[0081] Comparative Example 4: A low-temperature sealing high-temperature resistant and water-resistant PE film, which differs from Example 1 in that the raw material dosage is as shown in Table 2, and MLLDPE is used instead of HDPE in the outer layer.

[0082] Comparative Example 5: A low-temperature sealing high-temperature resistant and water-blocking PE film, which differs from Example 1 in that the raw material dosage is as shown in Table 2, and no MLLDPE is added to the outer layer.

[0083] Comparative Example 6: A low-temperature sealing high-temperature resistant and water-blocking PE film, which differs from Example 1 in that the raw material dosage is as shown in Table 2, and no MLLDPE and HDPE are added to the outer layer.

[0084] Table 2 shows the raw material usage for low-temperature sealing high-temperature resistant and water-blocking PE films in Comparative Examples 1-6.

[0085]

[0086]

[0087] The PE film was prepared according to the methods in the above examples and comparative examples, and the performance was tested according to the following methods. The test results are recorded in Table 3.

[0088] 1. Water vapor transmission rate: Tested according to GB / T26253-2010 "Determination of water vapor transmission rate of plastic films and sheets - Infrared detector method", with a test temperature of 38℃, a test humidity of 90%RH, a test flow rate of 20mL / min, and a test area of ​​50.24cm². 2 .

[0089] 2. Oxygen permeability: Tested according to GB / T19789-2022 "Test Method for Oxygen Permeability of Thin Films and Sheets - Coulometric Test", with a test temperature of 23 5SD, an oxygen partial pressure of 0.1 MPa, a test humidity of 0% RH, and a test area of ​​50.24 cm². 2 .

[0090] 3. Initial sealing temperature and heat sealing strength: The prepared PE film is laminated with a 12μm thick PET film, with the inner layer in contact with the PET film. The initial heat sealing temperature of the composite film is tested according to QB / T 2358-1998 (the temperature at which the heat sealing strength reaches 10N / 15mm is defined as the initial heat sealing temperature). The heat sealing pressure is 2Bar, the time is 1s, and the heat sealing strength of the film is tested under heat sealing conditions of 100℃.

[0091] 4. Tensile strength: Tested in accordance with GB / T13022-1991 "Test Method for Tensile Properties of Plastic Films".

[0092] 5. Heat shrinkage rate: Tested according to GB / T12027-2004 "Test method for dimensional change rate of plastic films and sheets under heating", with a test temperature of 130℃.

[0093] Table 3 Performance Testing of Low-Temperature Sealing High-Temperature Water-Blocking PE Film

[0094]

[0095]

[0096] As can be seen from Examples 1-3 and the data in Table 3, the PE film has a low initial sealing temperature, high heat sealing strength, and low water vapor and oxygen permeability, thus exhibiting good water and oxygen barrier effects. In addition, it has strong heat resistance.

[0097] Compared with Example 1, Example 4 did not add No. I MLLDPE in the inner layer and used No. II MLLDPE to replace No. I MLLDPE. Compared with Example 1, Example 5 used No. I MLLDPE to replace No. II MLLDPE. The data in Table 3 show that the PE films prepared in Example 4 and Example 5 are not as effective as those in Example 1 in terms of water and oxygen barrier properties. Moreover, the tensile strength is reduced, the initial sealing temperature is increased, and the heat sealing strength is reduced.

[0098] Compared with Example 1, Example 6 uses HDPE No. 1 instead of HDPE No. 2 in the inner, middle and outer layers. Compared with Example 1, Example 7 does not add HDPE No. 2. It can be seen that the PE films prepared in Examples 6 and 7 have reduced barrier properties against water vapor and oxygen, and the reduction in barrier properties is more significant in Example 7. At the same time, the heat shrinkage rate also increases and the heat resistance is weakened.

[0099] Compared with Example 1, Examples 8 and 9 used barrier masterbatches prepared by Preparation Example 1 and Preparation Example 2. Compared with Example 1, the PE films prepared in Examples 8 and 9 have improved water and oxygen barrier properties against water vapor and oxygen, improved tensile strength, reduced thermal shrinkage, and increased heat resistance.

[0100] Example 10 used the barrier masterbatch prepared in Preparation Example 3, which, compared to Preparation Example 1, did not contain the addition of tristearate-modified silica. Example 11 used the barrier masterbatch prepared in Preparation Example 4, which was not impregnated with aramid fiber dispersion. In Example 10, the barrier capacity of the PE film against water vapor and oxygen decreased, and the tensile strength weakened. In Example 11, the decrease in barrier capacity was more significant.

[0101] Compared with Example 1, Comparative Example 1 did not add MLLDPE to the inner layer. As shown in Table 3, the PE film prepared in Comparative Example 1 had a reduced ability to block water vapor and oxygen, and the sealing temperature was reduced, the heat sealing strength was reduced, and the tensile strength and heat resistance were weakened.

[0102] In Comparative Example 2, no barrier masterbatch was added to the inner, middle, and outer layers, only to the outer layer. In Comparative Example 3, the amount of barrier masterbatch used in the outer, inner, middle, and outer layers was 3 kg, with a uniform flux. Compared with Example 1, the barrier performance of Comparative Example 3 was higher than that of Comparative Example 2, while the barrier performance of Comparative Example 2 was the worst. It can be seen that setting the amount of barrier masterbatch from the outer layer to the inner layer in the order of high-low-high-low can significantly improve the water and oxygen barrier capabilities of the PE film.

[0103] Compared with Example 1, Comparative Example 4 uses MLLDPE instead of HDPE in the outer layer. Compared with Example 1, Comparative Example 5 does not add MLLDPE in the outer layer. Compared with Example 1, Comparative Example 6 does not add either MLLDPE or HDPE in the outer layer. The data in Table 3 shows that the PE film in Comparative Example 6 has the worst performance in all aspects, while Comparative Example 4 has the best performance. Using MLLDPE and HDPE together can improve the barrier performance of the PE film.

[0104] 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 low-temperature sealing, high-temperature resistant, water-blocking PE film, characterized in that, From the inside out, it consists of the following five layers: inner layer, second inner layer, middle layer, second outer layer, and outer layer; The inner layer comprises the following raw materials in parts by weight: 8-12 parts LDPE, 25-35 parts LLDPE, 55-65 parts MLLDPE, 0.6-1 parts PPA additive, 1.2-2 parts slip agent, and 5-6 parts opening agent; The innermost layer comprises the following raw materials in parts by weight: 90-100 parts HDPE, 1-2 parts barrier masterbatch, and 0.2-0.6 parts PPA additive; The intermediate layer comprises the following raw materials in parts by weight: 90-100 parts HDPE, 2.5-3.5 parts barrier masterbatch, and 0.2-0.6 parts PPA additive; The outermost layer comprises the following raw materials in parts by weight: 90-100 parts HDPE, 2-3 parts barrier masterbatch, and 0.2-0.6 parts PPA additive; The outer layer comprises the following raw materials in parts by weight: 35-45 parts LLDPE, 25-35 parts MLLDPE, 25-35 parts HDPE, 3.5-4 parts barrier masterbatch, 0.2-0.6 parts PPA additive, and 0.2-0.6 parts antioxidant; The innermost layer contains HDPE with a mass ratio of 1:1.5-2 and a density of 0.969 g / cm³. 3 HDPE No. 1 with a melt index of 1.2 g / 10 min and a density of 0.950 g / cm³ 3 HDPE No. 2 with a melt index of 0.9 g / 10 min; The intermediate layer contains HDPE with a mass ratio of 1:1.5-2 and a density of 0.969 g / cm³. 3 HDPE No. 1 with a melt index of 1.2 g / 10 min and a density of 0.956 g / cm³ 3 HDPE No. 3 with a density of 1g / 10min; The outermost layer contains HDPE with a mass ratio of 1:1.5-2 and a density of 0.969 g / cm³. 3 HDPE No. 1 with a melt index of 1.2 g / 10 min and a density of 0.958 g / cm³ 3 HDPE No. 4 with a density of 0.28 g / 10 min; The method for preparing the barrier masterbatch is as follows: Oxidized cellulose nanofibers were ultrasonically dispersed in deionized water for 1-2 hours to prepare a suspension with a concentration of 0.5-1wt%. Polyvinyl alcohol was dissolved in deionized water to prepare a polyvinyl alcohol aqueous solution with a concentration of 3.5-4wt%. Aramid fibers were broken into 3-5mm fragments, added to ethanol, ultrasonically removed impurities, and then dissolved to prepare a dispersion with a concentration of 0.5-0.7wt%. A polyvinyl alcohol aqueous solution and a suspension were mixed, stirred evenly, degassed, cast, and dried to obtain a matrix film. The mass ratio of oxidized nanocellulose filaments to polyvinyl alcohol was 1-1.5:

1. The substrate membrane is immersed and lifted in the dispersion 3-5 times, then immersed in a tert-butanol solution with a concentration of 50-55wt% at 60-70℃ for 1-3 minutes, removed and repeatedly washed with ultrapure water and anhydrous ethanol, freeze-dried, and pulverized to obtain the initial powder. The initial powder and No. 1 HDPE were mixed, melted, and granulated at a mass ratio of 0.03-0.06:

1.

2. The low-temperature sealing, high-temperature resistant, water-blocking PE film according to claim 1, characterized in that: The inner layer contains MLLDPE with a mass ratio of 1:1.5-2 and a density of 0.915 g / cm³. 3 MLLDPE of grade I with a melt index of 1 g / 10 min and a density of 0.913 g / cm³ 3 MLLDPE of type II with a melt index of 2 g / 10 min.

3. The low-temperature sealing, high-temperature resistant, water-blocking PE film according to claim 1, characterized in that: The density of LLDPE in the outer layer is 0.9188 g / cm³. 3 The melt flow index is 1.9 g / 10 min, and the density of MLLDPE is 0.94 g / cm³. 3 The melt flow index is 0.9 g / 10 min, and the density of HDPE is 0.961 g / cm³. 3 The melt flow index is 0.7 g / 10 min.

4. The low-temperature sealing, high-temperature resistant, water-blocking PE film according to claim 1, characterized in that: The density of LDPE in the inner layer is 0.924 g / cm³. 3 The melt flow index is 1.9 g / 10 min, and the density of LLDPE is 0.918 g / cm³. 3 The melt flow index is 2 g / 10 min.

5. The low-temperature sealing, high-temperature resistant, water-blocking PE film according to claim 1, characterized in that: The dispersion also contains glyceryl tristearate-modified silica, and the mass ratio of glyceryl tristearate-modified silica to aramid fibers in the dispersion is 0.1-0.2:

1.

6. The low-temperature sealing, high-temperature resistant, water-blocking PE film according to claim 1, characterized in that: The thickness ratio of the inner layer, the second inner layer, the middle layer, the second outer layer, and the outer layer is 2-2.5:1-1.5:2.8-3:1-1.5:2-2.

5.

7. The method for preparing the low-temperature sealing, high-temperature resistant, and water-resistant PE film according to any one of claims 1-6, characterized in that: Includes the following steps: The raw materials in the inner layer, the second inner layer, the middle layer, the second outer layer, and the outer layer are mixed evenly to obtain the inner layer material, the second outer layer material, the middle layer material, the second outer layer material, and the outer layer material. The inner layer material, the second outer layer material, the middle layer material, the second outer layer material, and the outer layer material are added into the hopper of the extruder, and then extruded, melted, cast, drawn, blown, pulled, and wound to produce a PE film.

8. The method for preparing the low-temperature sealing, high-temperature resistant, water-blocking PE film according to claim 7, characterized in that: The traction speed is 15-20 m / min, and the inflation ratio is 2-3:1.

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