Lightweight polyethylene liquid bag film and method of making same

Abstract

This invention relates to the field of liquid bag film preparation technology, and in particular to a lightweight polyethylene liquid bag film and its preparation method. The lightweight polyethylene liquid bag film comprises the following raw materials: polyolefin matrix resin, 3-(4-vinylphenoxy)-1-propylene, (3-buten-1-yl) acrylate, calcium lignosulfonate, carboxylated butadiene-acrylonitrile latex, trimethylolpropane triacrylate, initiator, crosslinking agent, accelerator, antioxidant, and slip agent. In the preparation process, 3-(4-vinylphenoxy)-1-propylene and (3-buten-1-yl) acrylate form a long-chain branched structure in the system, improving the tensile strength of the finished product. Simultaneously, trimethylolpropane triacrylate is added to increase the entanglement between molecular chains, and calcium lignosulfonate and carboxylated butadiene-acrylonitrile latex are added to dissipate impact energy and inhibit crack propagation. Therefore, the resulting polyethylene liquid bag film also exhibits significant impact resistance.

Description

Technical Field

[0001] This invention belongs to the field of liquid bag membrane preparation technology, and in particular relates to a lightweight polyethylene liquid bag membrane and its preparation method. Background Technology

[0002] Polyethylene liquid bags are a new type of flexible packaging container commonly used in the transportation of bulk liquids. Compared with traditional iron drums and plastic drums, they have advantages such as large loading capacity, low transportation costs, small storage space occupation, and convenient recycling. They are widely used in the transportation of liquids in the chemical, food, and pharmaceutical industries. Traditional polyethylene liquid bags are generally quite thick to ensure sufficient mechanical properties, leading to high raw material consumption and a large proportion of packaging weight. Therefore, the demand for lightweight polyethylene liquid bags has emerged. However, in practical applications, to reduce transportation costs and packaging material consumption, the industry often relies on thinning the liquid bag film to achieve lightweighting. But simple thinning easily leads to a decline in the mechanical properties of the liquid bag film. During loading and long-distance transportation, it is prone to cracking or even rupture due to tensile deformation and external impact, causing risks such as filling failure and liquid leakage. It is difficult to achieve a balance between lightweighting and mechanical properties, and even more difficult to meet the actual transportation requirements.

[0003] Patent application CN114193884A discloses a high-strength, lightweight antibacterial plastic film and its preparation method. The antibacterial plastic film is obtained by co-extrusion blow molding of an upper surface layer, an intermediate layer, and a lower surface layer. The upper and lower surface layers are made of the following components in parts by weight: 15-20 parts of metallocene polyethylene, 80 parts of low-density polyethylene, 5-10 parts of nano-calcium carbonate, 2 parts of fluoropolymer PPA, 0.15-0.6 parts of talc, 0.1-0.4 parts of erucamide, and 2-4 parts of antibacterial masterbatch. The intermediate layer is made of the following components in parts by weight: 90-95 parts of low-density polyethylene, 5-10 parts of nano-calcium carbonate, 2 parts of fluoropolymer PPA, 0.15-0.6 parts of talc, 0.1-0.4 parts of erucamide, 15-20 parts of barrier masterbatch, 15-20 parts of organically modified montmorillonite, and 3-6 parts of maleic anhydride-grafted polyethylene. This invention produces a high-strength and lightweight polyethylene film that also possesses high barrier and antibacterial properties. However, this patented film uses low-density polyethylene as a matrix and is filled with a large amount of inorganic fillers, including nano-calcium carbonate and organically modified montmorillonite, which easily leads to stress concentration. Although the addition of metallocene polyethylene and graft compatibilizers provides slight reinforcement, it still suffers from inherent defects such as poor tensile strength and impact resistance.

[0004] Therefore, developing a lightweight polyethylene liquid bag film that combines excellent tensile strength and impact resistance has become an urgent problem to be solved in this field. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a lightweight polyethylene liquid bag film and its preparation method to address the problems of poor tensile strength and impact resistance in existing polyethylene liquid bag film technology.

[0006] To achieve the above objectives, the present invention provides a lightweight polyethylene liquid bag film, comprising the following raw materials: Polyolefin matrix resins, vinyl functional monomers, acrylate monomers, lignin derivatives, synthetic latex, initiators, crosslinking agents, accelerators, antioxidants, and slip agents.

[0007] In some embodiments of the present invention, the polyolefin matrix resin is 100 parts by weight, the vinyl functional monomer is 1.2-1.6 parts by weight, the acrylate monomer is 2-2.9 parts by weight, the lignin derivative is 1-2.5 parts by weight, the synthetic latex is 5-8 parts by weight, the initiator is 0.1-0.3 parts by weight, the crosslinking agent is 0.5-2 parts by weight, the accelerator is 1.6-2.4 parts by weight, the antioxidant is 0.5-1 parts by weight, and the slip agent is 0.5-2 parts by weight.

[0008] In some embodiments of the present invention, the polyolefin matrix resin comprises linear low-density polyethylene, high-density polyethylene and metallocene linear low-density polyethylene in a mass ratio of 2-4:8-10:1-2.

[0009] In some preferred embodiments of the present invention, the vinyl functional monomer is 3-(4-vinylphenoxy)-1-propene. 3-(4-vinylphenoxy)-1-propene is a monomer with non-equivalent double bonds. The present invention incorporates 3-(4-vinylphenoxy)-1-propene, whose highly reactive double bonds capture the macromolecular free radicals generated by initiators or irradiation in the polyolefin matrix resin, thereby improving the stability of macromolecular free radicals, reducing the significant decrease in molecular weight, and protecting the mechanical properties of the material. At the same time, the less reactive double bond structure in the 3-(4-vinylphenoxy)-1-propene monomer can also serve as a structural basis to provide reaction sites for branching in the system, effectively promoting the formation of branched structures in the system.

[0010] In some preferred embodiments of the present invention, the acrylate monomers include (3-buten-1-yl) acrylate and trimethylolpropane triacrylate; Further, the (3-buten-1-yl) acrylate is 1-1.4 parts by weight, and the trimethylolpropane triacrylate is 1-1.5 parts by weight; The alkyl double bond of (3-buten-1-yl) acrylate has a slow reaction rate, so it can become a potential branching reaction site in the form of a dangling double bond in the system, which enriches the number of branching sites on the main chain of polyolefin matrix resin. At the same time, (3-buten-1-yl) acrylate can further react with macromolecular free radicals in the system to form a long-chain branched structure, which effectively improves the branching density of the system. Trimethylolpropane triacrylate is a multifunctional monomer containing three acrylate double bonds. These double bonds act as bridges to connect the molecular chains of polyolefin matrix resins, increasing the degree of entanglement between molecular chains and restricting chain slip. When the material is subjected to impact, the entangled molecular chains need to absorb more energy to break, thereby improving the material's impact resistance.

[0011] In some preferred embodiments of the present invention, the lignin derivative is calcium lignin sulfonate, which contains sulfonic acid groups, as well as polar functional groups such as phenolic hydroxyl groups, alcoholic hydroxyl groups, carboxyl groups, and carbonyl groups. These groups give calcium lignin sulfonate significant polarity. At the same time, calcium lignin sulfonate can also act as a physical crosslinking point and part of the stress concentration point in the system, and its ability to absorb stress during fracture effectively increases the impact resistance of the system.

[0012] In some preferred embodiments of the present invention, the synthetic latex is a carboxylated nitrile butadiene latex, which is uniformly distributed in the polyethylene matrix. When the material is subjected to impact, the carboxylated nitrile butadiene latex can become a stress concentration point, inducing the matrix to produce crazes or shear bands, thereby consuming a large amount of impact energy and preventing stress concentration and rapid crack propagation.

[0013] In some embodiments of the present invention, the initiator comprises 2-isopropylthioxanthone (ITX) and 2,5-dimethyl-2,5-di-tert-butylperoxide (DHBP) in a mass ratio of 1:1-1.5.

[0014] In some embodiments of the present invention, the crosslinking agent includes at least one of triallyl isocyanurate (TAIC), trimethylolpropane trimethacrylate (TMPTMA), and triallyl cyanurate (TAC).

[0015] In some embodiments of the present invention, the accelerator is ZDMC.

[0016] In some embodiments of the present invention, the antioxidant comprises antioxidant 1010 and antioxidant 168 in equal mass.

[0017] In some preferred embodiments of the present invention, the slip agent is erucamide.

[0018] In some embodiments of the present invention, the lightweight polyethylene liquid bag film further includes the following raw material: 40-55 parts by weight of acetone.

[0019] The present invention also provides a method for preparing the above-mentioned lightweight polyethylene liquid bag film, comprising the following steps: (1) Mix 3-(4-vinylphenoxy)-1-propylene, (3-buten-1-yl) acrylate, trimethylolpropane triacrylate, initiator, crosslinking agent, accelerator and acetone and stir to form a homogeneous solution to obtain a mixture; Calcium lignosulfonate was dried under controlled temperature to obtain dried calcium lignosulfonate. After mixing the polyolefin matrix resin, the mixture is added dropwise while stirring. After the addition is complete, the acetone is evaporated in a fume hood to obtain the mixture. (2) The mixture, dried calcium lignosulfonate, carboxylated nitrile latex, slip agent and antioxidant are mixed evenly in a mixer and then added to a twin-screw extruder for melt blending, extrusion and granulation to obtain composite granules; (3) The composite granules are cooled by air ring, blown, cooled and shaped, pulled and wound to obtain primary membrane material. The primary membrane material is irradiated under argon protection to obtain irradiated membrane material. After the irradiated membrane material is placed at room temperature, it is trimmed and wound to obtain lightweight polyethylene liquid bag film.

[0020] The lightweight polyethylene liquid bag film prepared by this invention forms a long-chain branched structure in the system with 3-(4-vinylphenoxy)-1-propylene and (3-buten-1-yl) acrylate, which significantly improves the tensile strength of the finished product. At the same time, trimethylolpropane triacrylate is added to increase the degree of entanglement between molecular chains in the system, and calcium lignin sulfonate and carboxylated butadiene nitrile latex are added to dissipate impact energy and inhibit crack propagation. Therefore, the finished polyethylene liquid bag film also has significant impact resistance.

[0021] In some embodiments of the present invention, the temperature-controlled drying in step (1) is drying at 60-80℃ for 6-8 hours.

[0022] In some embodiments of the present invention, in the twin-screw extruder described in step (2), the screw speed is 55-70 r / min; The temperatures of each zone of the twin-screw extruder are as follows: Zone 1: 165-175℃, Zone 2: 180-185℃, Zone 3: 190-195℃, and Die head: 185-190℃.

[0023] In some embodiments of the present invention, the irradiation in step (3) is γ-ray irradiation generated using a Co60 cobalt source; The time for placing the item at room temperature is 24-48 hours.

[0024] In some preferred embodiments of the present invention, the irradiation dose is 30-120 kgy and the irradiation time is 20-30 min.

[0025] The beneficial effects of this invention are: (1) In this invention, the stability of the free radicals of the system is enhanced by 3-(4-vinylphenoxy)-1-propylene and basic branching sites are provided. The number of branching sites and the branching density of the system are increased by the allylic double bond of (3-buten-1-yl) acrylate. Therefore, the number of long-chain branched structures formed in the system increases. At the same time, the molecular chain entanglement brought about by the long-chain branched structure can significantly improve the tensile strength of the system. Therefore, the polyethylene liquid bag film product obtained by this invention has excellent tensile strength properties.

[0026] (2) The present invention adds trimethylolpropane triacrylate to increase the degree of entanglement between molecular chains in the system. At the same time, calcium lignosulfonate containing polar groups and non-polar aromatic ring structures effectively promotes the dispersion of carboxylated nitrile latex in the matrix, strengthens the interfacial interaction between carboxylated nitrile latex and the matrix, and increases interfacial bonding. The dispersed carboxylated nitrile latex can dissipate impact energy through elastic deformation in the system and inhibit crack propagation. Therefore, the polyethylene liquid bag film product obtained has significant impact resistance.

[0027] (3) The polyethylene liquid bag film prepared by the present invention has outstanding tensile strength and impact resistance. It can withstand the weight of the liquid itself and the continuous pressure between items during transportation and stacking, prevent the bag from stretching and deforming, bursting and leaking, and is suitable for handling and stacking operations. At the same time, it can resist the impact of bumps and drops during transportation, reduce film damage, and fully ensure the safety of liquid storage and transportation. Moreover, the liquid bag film of the present invention is suitable for the packaging needs of various liquids.

[0028] (4) The formulation of this invention uses a low-density polyolefin matrix resin as the base matrix. Relying on the low-density nature of the polyolefin hydrocarbon skeleton and a small amount of modified raw materials, it achieves the lightweight characteristics of polyethylene liquid bag film while satisfying the material's good mechanical properties. Detailed Implementation

[0029] The claims of the present invention will be further described in detail below with reference to specific embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of protection of the claims of the present invention are still within the scope of protection of the claims of the present invention.

[0030] Information on some of the raw materials used in this invention is as follows: Linear low-density polyethylene, grade: 1001XV, purchased from: Nanjing Praxair New Material Technology Co., Ltd. High-density polyethylene, item number: P77512, purchased from: Shanghai Jizhi Biochemical Technology Co., Ltd.; Metallocene linear low-density polyethylene, grade: GM1835CAX01, purchased from: Dongguan Jinshixiang Plastic Raw Materials Co., Ltd. (3-Buten-1-yl) acrylate, CAS No.: 27819-07-4, grade: SY406116, purchased from: Shaoyuan Technology (Shanghai) Co., Ltd.; Calcium lignosulfonate, model: C49-11363, purchased from: Shanghai Chuangsai Technology Co., Ltd.; Carboxylated nitrile butadiene latex, grade: 730, purchased from: Anqing Hualan Technology Co., Ltd.; The above will not be repeated hereafter.

[0031] Example 1 A lightweight polyethylene liquid bag film comprises the following raw materials in parts by weight: 17.4 parts by weight of linear low-density polyethylene, 69.6 parts by weight of high-density polyethylene, 13 parts by weight of metallocene linear low-density polyethylene, 1.4 parts by weight of 3-(4-vinylphenoxy)-1-propylene, 1.2 parts by weight of (3-buten-1-yl) acrylate, 2.5 parts by weight of calcium lignosulfonate, 6.5 parts by weight of carboxylated butadiene-acrylonitrile latex, 1 part by weight of trimethylolpropane triacrylate, 0.12 parts by weight of 2-isopropylthioxanthone, 0.18 parts by weight of 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, 0.25 parts by weight of triallyl isocyanurate, 0.25 parts by weight of trimethylolpropane trimethacrylate, 2.4 parts by weight of accelerator ZDMC, 0.25 parts by weight of antioxidant 1010, 0.25 parts by weight of antioxidant 168, 2 parts by weight of erucamide, and 44 parts by weight of acetone. The preparation method of lightweight polyethylene liquid bag film specifically includes the following steps: (1) Mix 3-(4-vinylphenoxy)-1-propylene, (3-buten-1-yl) acrylate, trimethylolpropane triacrylate, 2-isopropylthioxanthone, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, triallyl isocyanurate, trimethylolpropane trimethacrylate, accelerator ZDMC and acetone and stir to form a homogeneous solution to obtain a mixture; Calcium lignosulfonate was dried at 65℃ for 6 hours to obtain dried calcium lignosulfonate. Linear low-density polyethylene, high-density polyethylene and metallocene linear low-density polyethylene are mixed and then added dropwise while stirring. After the addition is complete, acetone is evaporated in a fume hood to obtain the mixture. (2) After the mixture, dried calcium lignosulfonate, carboxylated nitrile latex, erucamide, antioxidant 1010 and antioxidant 168 are mixed evenly in a mixer, they are added to a twin-screw extruder with a screw speed of 70 r / min, a zone 1 temperature of 170℃, a zone 2 temperature of 180℃, a zone 3 temperature of 190℃ and a die head temperature of 185℃. The mixture is then melt-blended, extruded and granulated to obtain composite granules. (3) The composite granules are cooled by air ring, blown, cooled and shaped, pulled and wound to obtain a primary membrane material with a thickness of 230μm. The primary membrane material is irradiated for 30min with γ-rays generated by Co60 cobalt source under argon protection to obtain irradiated membrane material. After the irradiated membrane material is placed at room temperature for 48h, it is trimmed and wound to obtain lightweight polyethylene liquid bag film.

[0032] Example 2 A lightweight polyethylene liquid bag film comprises the following raw materials in parts by weight: 22.2 parts by weight of linear low-density polyethylene, 70.4 parts by weight of high-density polyethylene, 7.4 parts by weight of metallocene linear low-density polyethylene, 1.5 parts by weight of 3-(4-vinylphenoxy)-1-propylene, 1 part by weight of (3-buten-1-yl) acrylate, 2.1 parts by weight of calcium lignosulfonate, 7.3 parts by weight of carboxylated butadiene-acrylonitrile latex, 1.2 parts by weight of trimethylolpropane triacrylate, 0.05 parts by weight of 2-isopropylthioxanthone, 0.05 parts by weight of 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, 0.58 parts by weight of triallyl isocyanurate, 0.29 parts by weight of triallyl cyanurate, 1.8 parts by weight of accelerator ZDMC, 0.31 parts by weight of antioxidant 1010, 0.31 parts by weight of antioxidant 168, 0.5 parts by weight of erucamide, and 47.5 parts by weight of acetone. The preparation method of lightweight polyethylene liquid bag film specifically includes the following steps: (1) Mix 3-(4-vinylphenoxy)-1-propylene, (3-buten-1-yl) acrylate, trimethylolpropane triacrylate, 2-isopropylthioxanthone, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, triallyl isocyanurate, triallyl cyanurate, accelerator ZDMC and acetone and stir to form a homogeneous solution to obtain a mixture; Calcium lignosulfonate was dried at 70℃ for 7 hours to obtain dried calcium lignosulfonate. Linear low-density polyethylene, high-density polyethylene and metallocene linear low-density polyethylene are mixed and then added dropwise while stirring. After the addition is complete, acetone is evaporated in a fume hood to obtain the mixture. (2) After the mixture, dried calcium lignosulfonate, carboxylated nitrile latex, erucamide, antioxidant 1010 and antioxidant 168 are mixed evenly in a mixer, they are added to a twin-screw extruder with a screw speed of 55 r / min, zone 1 temperature of 165℃, zone 2 temperature of 180℃, zone 3 temperature of 190℃ and die head temperature of 185℃ for melt blending, extrusion and granulation to obtain composite granules; (3) The composite granules are cooled by air ring, blown, cooled and shaped, pulled and wound to obtain a primary membrane material with a thickness of 150μm. The primary membrane material is irradiated for 20 minutes with γ-rays generated by Co60 cobalt source under argon protection at an irradiation dose of 80kgy to obtain irradiated membrane material. After the irradiated membrane material is placed at room temperature for 24 hours, it is trimmed and wound to obtain lightweight polyethylene liquid bag film.

[0033] Example 3 A lightweight polyethylene liquid bag film comprises the following raw materials in parts by weight: 17.2 parts by weight of linear low-density polyethylene, 69 parts by weight of high-density polyethylene, 13.8 parts by weight of metallocene linear low-density polyethylene, 1.2 parts by weight of 3-(4-vinylphenoxy)-1-propylene, 1.4 parts by weight of (3-buten-1-yl) acrylate, 1.7 parts by weight of calcium lignosulfonate, 5 parts by weight of carboxylated butadiene-acrylonitrile latex, 1.1 parts by weight of trimethylolpropane triacrylate, 0.09 parts by weight of 2-isopropylthioxanthone, 0.11 parts by weight of 2,5-dimethyl-2,5-di-tert-butylperoxide, 0.53 parts by weight of triallyl isocyanurate, 1.1 parts by weight of trimethylolpropane trimethacrylate, 2 parts by weight of accelerator ZDMC, 0.5 parts by weight of antioxidant 1010, 0.5 parts by weight of antioxidant 168, 1.65 parts by weight of erucamide, and 40 parts by weight of acetone. The preparation method of lightweight polyethylene liquid bag film specifically includes the following steps: (1) Mix 3-(4-vinylphenoxy)-1-propylene, (3-buten-1-yl) acrylate, trimethylolpropane triacrylate, 2-isopropylthioxanthone, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, triallyl isocyanurate, trimethylolpropane trimethacrylate, accelerator ZDMC and acetone and stir to form a homogeneous solution to obtain a mixture; Calcium lignosulfonate was dried at 60℃ for 7.5 hours to obtain dried calcium lignosulfonate. Linear low-density polyethylene, high-density polyethylene and metallocene linear low-density polyethylene are mixed and then added dropwise while stirring. After the addition is complete, acetone is evaporated in a fume hood to obtain the mixture. (2) After the mixture, dried calcium lignosulfonate, carboxylated nitrile latex, erucamide, antioxidant 1010 and antioxidant 168 are mixed evenly in a mixer, they are added to a twin-screw extruder with a screw speed of 62r / min, a zone 1 temperature of 175℃, a zone 2 temperature of 185℃, a zone 3 temperature of 195℃ and a die head temperature of 190℃. The mixture is then melt-blended, extruded and granulated to obtain composite granules. (3) The composite granules are cooled by air ring, blown, cooled and shaped, pulled and wound to obtain a primary membrane material with a thickness of 250μm. The primary membrane material is irradiated for 25 minutes with γ-rays generated by Co60 cobalt source under argon protection at an irradiation dose of 120kgy to obtain irradiated membrane material. After the irradiated membrane material is placed at room temperature for 48 hours, it is trimmed and wound to obtain lightweight polyethylene liquid bag film.

[0034] Example 4 A lightweight polyethylene liquid bag film comprises the following raw materials in parts by weight: 27 parts by weight of linear low-density polyethylene, 60.8 parts by weight of high-density polyethylene, 12.2 parts by weight of metallocene linear low-density polyethylene, 1.6 parts by weight of 3-(4-vinylphenoxy)-1-propylene, 1.1 parts by weight of (3-buten-1-yl) acrylate, 1 part by weight of calcium lignosulfonate, 8 parts by weight of carboxylated butadiene-acrylonitrile latex, 1.5 parts by weight of trimethylolpropane triacrylate, 0.07 parts by weight of 2-isopropylthioxanthone, 0.08 parts by weight of 2,5-dimethyl-2,5-di-tert-butylperoxide, 1.5 parts by weight of trimethylolpropane trimethacrylate, 0.5 parts by weight of triallyl cyanurate, 1.6 parts by weight of accelerator ZDMC, 0.37 parts by weight of antioxidant 1010, 0.37 parts by weight of antioxidant 168, 0.9 parts by weight of erucamide, and 55 parts by weight of acetone. The preparation method of lightweight polyethylene liquid bag film specifically includes the following steps: (1) Mix 3-(4-vinylphenoxy)-1-propene, (3-buten-1-yl) acrylate, trimethylolpropane triacrylate, 2-isopropylthioxanthone, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, trimethylolpropane trimethacrylate, triallyl cyanurate, accelerator ZDMC and acetone and stir to form a homogeneous solution to obtain a mixture; Calcium lignosulfonate was dried at 75℃ for 8 hours to obtain dried calcium lignosulfonate. Linear low-density polyethylene, high-density polyethylene and metallocene linear low-density polyethylene are mixed and then added dropwise while stirring. After the addition is complete, acetone is evaporated in a fume hood to obtain the mixture. (2) After the mixture, dried calcium lignosulfonate, carboxylated nitrile latex, erucamide, antioxidant 1010 and antioxidant 168 are mixed evenly in a mixer, they are added to a twin-screw extruder with a screw speed of 59 r / min, zone 1 temperature of 165℃, zone 2 temperature of 185℃, zone 3 temperature of 190℃ and die head temperature of 190℃ for melt blending, extrusion and granulation to obtain composite granules; (3) The composite granules are cooled by air ring, blown, cooled and shaped, pulled and wound to obtain a primary membrane material with a thickness of 200μm. The primary membrane material is irradiated for 30 minutes with γ-rays generated by Co60 cobalt source under argon protection at an irradiation dose of 50kgy to obtain irradiated membrane material. The irradiated membrane material is placed at room temperature for 36 hours, then trimmed and wound to obtain lightweight polyethylene liquid bag film.

[0035] Example 5 A lightweight polyethylene liquid bag film comprises the following raw materials in parts by weight: 26.5 parts by weight of linear low-density polyethylene, 64.4 parts by weight of high-density polyethylene, 9.1 parts by weight of metallocene linear low-density polyethylene, 1.3 parts by weight of 3-(4-vinylphenoxy)-1-propylene, 1.3 parts by weight of (3-buten-1-yl) acrylate, 1.4 parts by weight of calcium lignosulfonate, 5.8 parts by weight of carboxylated butadiene-acrylonitrile latex, 1.4 parts by weight of trimethylolpropane triacrylate, 0.12 parts by weight of 2-isopropylthioxanthone, 0.13 parts by weight of 2,5-dimethyl-2,5-di-tert-butylperoxide, 0.8 parts by weight of triallyl isocyanurate, 0.45 parts by weight of triallyl cyanurate, 2.2 parts by weight of accelerator ZDMC, 0.44 parts by weight of antioxidant 1010, 0.44 parts by weight of antioxidant 168, 1.25 parts by weight of erucamide, and 51 parts by weight of acetone. The preparation method of lightweight polyethylene liquid bag film specifically includes the following steps: (1) Mix 3-(4-vinylphenoxy)-1-propylene, (3-buten-1-yl) acrylate, trimethylolpropane triacrylate, 2-isopropylthioxanthone, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, triallyl isocyanurate, triallyl cyanurate, accelerator ZDMC and acetone and stir to form a homogeneous solution to obtain a mixture; Calcium lignosulfonate was dried at 80℃ for 6.5 hours to obtain dried calcium lignosulfonate. Linear low-density polyethylene, high-density polyethylene and metallocene linear low-density polyethylene are mixed and then added dropwise while stirring. After the addition is complete, acetone is evaporated in a fume hood to obtain the mixture. (2) After the mixture, dried calcium lignosulfonate, carboxylated nitrile latex, erucamide, antioxidant 1010 and antioxidant 168 are mixed evenly in a mixer, they are added to a twin-screw extruder with a screw speed of 66 r / min, a zone 1 temperature of 170℃, a zone 2 temperature of 180℃, a zone 3 temperature of 195℃ and a die head temperature of 185℃. The mixture is then melt-blended, extruded and granulated to obtain composite granules. (3) The composite granules are cooled by air ring, blown, cooled and shaped, pulled and wound to obtain a primary membrane material with a thickness of 100μm. The primary membrane material is irradiated for 25 minutes with γ-rays generated by Co60 cobalt source under argon protection at a dose of 100kgy to obtain irradiated membrane material. After the irradiated membrane material is placed at room temperature for 48 hours, it is trimmed and wound to obtain lightweight polyethylene liquid bag film.

[0036] Comparative Example 1 Compared with Example 3, the difference is that 3-(4-vinylphenoxy)-1-propene is not added, while the other operating steps and parameters remain unchanged.

[0037] Comparative Example 2 Compared with Example 3, the difference is that (3-buten-1-yl) acrylate is not added, while the other operation steps and parameters remain unchanged.

[0038] Comparative Example 3 Compared with Example 3, the difference is that trimethylolpropane triacrylate is not added, while the other operation steps and parameters remain unchanged.

[0039] Comparative Example 4 Compared with Example 3, the difference is that calcium lignosulfonate is not added, while the other operation steps and parameters remain unchanged.

[0040] Comparative Example 5 Compared with Example 3, the difference is that no carboxylated nitrile latex is added, while the other operation steps and parameters remain unchanged.

[0041] Tests and trials (1) Tensile strength test: In accordance with GB / T 1040.3-2006, a universal testing machine was used with a tensile speed of 500 mm / min to test the longitudinal (MD) and transverse (TD) tensile strength of the lightweight polyethylene liquid bag film prepared in Examples 1-5 and Comparative Examples 1-5. The test results are shown in Table 1.

[0042] (2) Impact resistance test: Referring to GB / T 1043.1-2008, the temperature was 25℃, V-notch, the sample size was 80mm×10mm×4mm, and the notch depth was 2mm. The lightweight polyethylene liquid bag film prepared in Examples 1-5 and Comparative Examples 1-5 was subjected to notched impact strength test. The test results are shown in Table 1.

[0043] Table 1

[0044] As shown in Table 1, the lightweight polyethylene liquid bag film prepared by this invention exhibits excellent tensile strength and impact resistance. Specifically, data analysis reveals that the longitudinal tensile strength values ​​of Examples 1-5 are all ≥81 MPa, and the transverse tensile strength values ​​are all ≥90 MPa, showing a significant improvement compared to the comparative examples. Furthermore, the notched impact strength values ​​of Examples 1-5 are all ≥13 kJ / m², also showing a substantial improvement compared to the comparative examples. The finished product of this invention meets the mechanical strength requirements for lightweight liquid bag films.

[0045] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A lightweight polyethylene liquid bag film, characterized in that, Including the following raw materials: 100 parts by weight of polyolefin matrix resin, 1.2-1.6 parts by weight of vinyl functional monomers, 2-2.9 parts by weight of acrylate monomers, 1-2.5 parts by weight of lignin derivatives, 5-8 parts by weight of synthetic latex, 0.1-0.3 parts by weight of initiator, 0.5-2 parts by weight of crosslinking agent, 1.6-2.4 parts by weight of accelerator, 0.5-1 parts by weight of antioxidant, and 0.5-2 parts by weight of slip agent.

2. The lightweight polyethylene liquid bag film according to claim 1, characterized in that, The polyolefin matrix resin comprises linear low-density polyethylene, high-density polyethylene, and metallocene linear low-density polyethylene in a mass ratio of 2-4:8-10:1-2.

3. The lightweight polyethylene liquid bag film according to claim 1, characterized in that, The vinyl functional monomer is 3-(4-vinylphenoxy)-1-propylene.

4. The lightweight polyethylene liquid bag film according to claim 1, characterized in that, The acrylate monomers include 1-1.4 parts by weight of (3-buten-1-yl) acrylate and 1-1.5 parts by weight of trimethylolpropane triacrylate.

5. The lightweight polyethylene liquid bag film according to claim 1, characterized in that, The lignin derivative is calcium lignin sulfonate.

6. The lightweight polyethylene liquid bag film according to claim 1, characterized in that, The synthetic latex is a carboxylated butadiene nitrile latex.

7. The lightweight polyethylene liquid bag film according to claim 1, characterized in that, The initiator comprises 2-isopropylthioxanthone and 2,5-dimethyl-2,5-di-tert-butylperoxyhexane in a mass ratio of 1:1-1.5; the crosslinking agent comprises at least one of triallyl isocyanurate, trimethylolpropane trimethacrylate, and triallyl cyanurate; the accelerator is accelerator ZDMC; the antioxidant comprises antioxidant 1010 and antioxidant 168 in equal mass; and the slip agent is erucamide.

8. A method for preparing a lightweight polyethylene liquid bag film as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Mix 3-(4-vinylphenoxy)-1-propylene, (3-buten-1-yl) acrylate, trimethylolpropane triacrylate, initiator, crosslinking agent, accelerator and acetone and stir to form a homogeneous solution to obtain a mixture; dry calcium lignosulfonate at controlled temperature to obtain dried calcium lignosulfonate; mix polyolefin matrix resin and add the mixture dropwise while stirring. After the mixture is added, evaporate the acetone in a fume hood to obtain a mixture. (2) The mixture, dried calcium lignosulfonate, carboxylated nitrile latex, slip agent and antioxidant are mixed evenly in a mixer and then added to a twin-screw extruder for melt blending, extrusion and granulation to obtain composite granules; (3) The composite granules are cooled by air ring, blown, cooled and shaped, pulled and wound to obtain primary membrane material. The primary membrane material is irradiated under argon protection to obtain irradiated membrane material. After the irradiated membrane material is placed at room temperature, it is trimmed and wound to obtain lightweight polyethylene liquid bag film.

9. The method for preparing the lightweight polyethylene liquid bag film according to claim 8, characterized in that, The temperature-controlled drying in step (1) is to dry at 60-80℃ for 6-8 hours; In the twin-screw extruder described in step (2), the screw speed is 55-70 r / min; The temperatures of each zone of the twin-screw extruder are as follows: Zone 1: 165-175℃, Zone 2: 180-185℃, Zone 3: 190-195℃, and Die head: 185-190℃.

10. The method for preparing the lightweight polyethylene liquid bag film according to claim 8, characterized in that, The irradiation in step (3) is γ-ray irradiation generated by a Co60 cobalt source; the time for placing at room temperature is 24-48 hours. The irradiation dose is 30-120 kgy, and the time is 20-30 min.

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