A high-strength puncture-resistant polyethylene bubble bag and a method for producing the same

Abstract

The application discloses a high-strength puncture-resistant polyethylene bubble bag and a preparation method thereof. The high-strength puncture-resistant composite polyethylene bubble bag can be recycled, and is prepared by using high-density polyethylene as a base body, modifying polyethylene materials with different molecular structures and processing aids, and regulating the rheological behavior and crystallization behavior of different layer structure components through different processing modes. The application makes full use of the regulation of formula design and different processing technologies on the crystallization behavior and performance of polyethylene, and specifically designs the high-strength and high-toughness puncture-resistant outer layer polyethylene cross film, the middle layer bubble film and the high-strength and high-heat-sealing-strength inner layer heat-sealing film, so that the mechanical properties and heat-sealing strength of the bubble film are obviously improved, and the bubble film can be applied to the field of automobile accessory packaging and transportation.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and relates to bubble bags, and more particularly to a high-strength, puncture-resistant polyethylene bubble bag and its preparation method. Background Technology

[0002] To meet environmental protection requirements, automakers have primarily focused their R&D efforts on reducing vehicle emissions, lowering energy consumption, and developing new energy vehicles, aiming to create "green and environmentally friendly cars" that comply with environmental protection standards. However, they have lacked investment and R&D in the greening of automotive parts packaging. The hallmarks of a green car are: low environmental pollution, improved power sources, and recycling. Therefore, prioritizing the greening of automotive parts packaging is also a crucial focus, ensuring that "green and environmentally friendly cars" truly live up to their name in every aspect. The use of automotive parts packaging materials can significantly reduce the breakage rate of automotive parts during transportation, meeting transportation requirements. However, traditional bubble wrap, mainly made of linear low-density polyethylene and polypropylene, suffers from low strength, low processing efficiency, and increased difficulty in recycling due to the significant mismatch in physical and processing properties between different materials. After use, it is often directly discarded, causing serious environmental harm and leading to plastic pollution. Therefore, there is an urgent need to develop high-performance, lightweight, and easily recyclable multi-layer composite polyethylene bubble bags for automotive parts packaging.

[0003] High-density polyethylene (HDPE) has high crystallinity and a fast crystallization temperature, as well as a high service temperature. It also exhibits good hardness, airtightness, mechanical strength, and impact resistance. HDPE is used in bubble wrap specifically for packaging automotive parts, which not only imparts superior mechanical properties but also significantly improves processing performance.

[0004] However, high-density polyethylene also has its shortcomings, especially the poor puncture resistance of the film. Moreover, a single-structure high-density polyethylene cannot meet the requirements of multiple functions. Therefore, it is necessary to modify it by compounding. However, the compatibility between different polyethylene materials is not very high. Compatibility will directly affect the mechanical properties and service life of the material. Therefore, it is necessary to design different layers of polyethylene materials separately and use multilayer composite technology to effectively combine polyethylene resins with different molecular structures to solve the problems of multilayer film composites such as puncture resistance, impact resistance, wear resistance and rigidity.

[0005] Chinese patent publication number CN107936345A, published on April 20, 2018, entitled "Medical Anti-corrosion Bubble Packaging Film and Its Preparation Method", discloses the modification of polyethylene to improve the mechanical strength of bubble film. However, the modification method is complicated and cumbersome, with a long reaction cycle and low production efficiency, and is not suitable for large-scale production and promotion.

[0006] Chinese patent publication number CN112208178A, published on January 12, 2021, entitled "Polyolefin Film for Express Bubble Bags and its Preparation Method Thereof," discloses a method of using polypropylene to increase the stiffness of polyethylene film to prepare a three-layer co-extruded film composited with bubble film. This method uses a large amount of polypropylene and its copolymers, and the material after being composited with bubble film is difficult to recycle and reuse. Moreover, it does not take into account issues such as the composite and heat sealing of the film and bubble film.

[0007] Chinese patent publication number CN108177409A, published on June 19, 2018, entitled "Invention Patent for Polyethylene Heat Shrink Film", discloses a method for preparing a five-layer co-extruded heat shrink film using different polyethylene materials. By adjusting the content of different types of polyethylene in each layer, the toughness of the heat shrink film can be increased synergistically. However, this method does not take into account the composite strength between the layers and is not suitable for the production of bubble wrap.

[0008] Chinese patent publication number CN112208114A, published on January 12, 2021, entitled "Preparation Method of High-Density Polyethylene Cross-Layer Film," discloses a method for first preparing a tubular film, then subjecting the film to directional stretching and annealing, followed by helical cutting of the tubular film, and finally cross-laminating the resulting films to obtain a traditional cross-laminated film. This method is relatively cumbersome, requiring multiple machines on a production line, thus increasing production costs. Summary of the Invention

[0009] The technical problems to be solved by this invention include: the poor puncture resistance of existing films; the inability of single-structure high-density polyethylene to meet multifunctional requirements, thus requiring compound modification, but the compatibility between different polyethylene materials is not very high, and compatibility directly affects the mechanical properties and service life of the materials.

[0010] Therefore, the present invention provides a high-strength puncture-resistant polyethylene bubble bag and its preparation method. The present invention uses high-density polyethylene as the matrix, and modifies it using polyethylene materials with different molecular structures and processing aids. By controlling the rheological behavior and crystallization behavior of different layer structure components through different processing methods, a recyclable high-strength puncture-resistant composite polyethylene bubble bag is finally obtained.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] This invention provides a high-strength, puncture-resistant polyethylene bubble bag, comprising a composite outer layer of high-strength polyethylene cross-linked film, a middle layer of polyethylene cast bubble film, and an inner layer of polyethylene heat-sealing film. The outer layer of high-strength polyethylene cross-linked film is made from the following raw materials: high-density polyethylene, metallocene medium-density polyethylene, bimodal high-density polyethylene, compatibilizer, antioxidant, and light stabilizer. The middle layer of polyethylene cast bubble film is made from the following raw materials: high-density polyethylene, metallocene medium-density polyethylene, bimodal high-density polyethylene, ethylene-octene random copolymer, inorganic filler, organic nucleating agent, compatibilizer, slip agent, antioxidant, and light stabilizer. The inner layer of polyethylene heat-sealing film is made from the following raw materials: bimodal linear low-density polyethylene, highly branched linear low-density polyethylene, metallocene polyethylene, and compatibilizer.

[0013] As a preferred embodiment of the present invention, the raw materials of the outer high-strength polyethylene cross-linked film, by weight, are: 100 parts high-density polyethylene, 10-20 parts metallocene medium-density polyethylene, 10-20 parts bimodal high-density polyethylene, 1-3 parts compatibilizer, 0.1-1 parts antioxidant and 0.1-1 parts light stabilizer.

[0014] As a preferred embodiment of the present invention, the raw materials of the middle layer polyethylene cast bubble film, by weight, are: 100 parts high-density polyethylene, 10-20 parts metallocene medium-density polyethylene, 10-20 parts bimodal high-density polyethylene, 5-10 parts ethylene-octene random copolymer, 5-10 parts inorganic filler, 0.1-0.5 parts organic nucleating agent, 1-3 parts compatibilizer, 0.01-0.2 parts slip agent, 0.1-1 parts antioxidant and 0.1-1 parts light stabilizer.

[0015] As a preferred embodiment of the present invention, the raw materials of the inner polyethylene heat-sealing film, by weight, are: 100 parts bimodal linear low-density polyethylene, 5-10 parts highly branched linear low-density polyethylene, 10-20 parts metallocene polyethylene and 1-3 parts compatibilizer.

[0016] In a preferred embodiment of the present invention, the density of the high-density polyethylene is 0.941-0.965 g / cm³. 3 The melt index is 2.0-4.0 g / 10 min, and the weight-average molecular weight is 200,000-300,000.

[0017] The density of the metallocene medium-density polyethylene is 0.926-0.930 g / cm³. 3 The melt index is 1.0-2.0 g / 10 min, and the weight-average molecular weight is 100,000-150,000.

[0018] The density of the bimodal high-density polyethylene is 0.945-0.960 g / cm³. 3The melt index is 1.0-2.0 g / 10 min, and the ratio of the relative content of high molecular weight peak to the relative content of low molecular weight peak is 1.0-1.4.

[0019] In a preferred embodiment of the present invention, the density of the ethylene-octene random copolymer is 0.870-0.920 g / cm³. 3 The melt flow index is 2.0-5.0 g / 10 min, the weight-average molecular weight is 150,000-200,000, and the octene content is 20-25%. The inorganic filler is one or more of calcium carbonate, silicon dioxide, talc, titanium dioxide, montmorillonite, kaolin, bentonite, diatomaceous earth, and barium sulfate, with a particle size of 50-200 nm. The organic nucleating agent is one or more of sorbitol-based nucleating agents, phosphate-based nucleating agents, and rosin-based nucleating agents. The slip agent is one or more of migratory primary amide slip agents such as isostearamide, stearamide, behenamide, oleamide, and erucamide. The compatibilizer is a graft copolymer with glycidyl methacrylate, butyl acrylate, or maleic anhydride, with a grafting rate of 1-1.5%.

[0020] In a preferred embodiment of the present invention, the density of the bimodal linear low-density polyethylene is 0.910-0.930 g / cm³. 3 The melt index is 2.0-3.0 g / 10 min, and the ratio of the relative content of high molecular weight peaks to the relative content of low molecular weight peaks is 0.7-0.9.

[0021] The density of the highly branched linear low-density polyethylene is 0.910-0.925 g / cm³. 3 The melt index is 2.0-3.0 g / 10 min, the weight-average molecular weight is 200,000-250,000, and the branching content is 14-17‰.

[0022] The metallocene polyethylene is metallocene linear low-density polyethylene or metallocene ultra-low-density polyethylene;

[0023] The metallocene linear low-density polyethylene described has a melt index of 1.0-2.0 g / 10 min and a density of 0.910-0.927 g / cm³. 3 The weight-average molecular weight is 150,000-200,000;

[0024] The metallocene-coated ultra-low density polyethylene has a melt index of 1.0-2.0 g / 10 min and a density of 0.900-0.910 g / cm³. 3 The weight-average molecular weight is 150,000-200,000.

[0025] As a preferred embodiment of the present invention, the antioxidant is one or more of antioxidant 168, antioxidant 300, antioxidant 330, antioxidant 627A, antioxidant B900, antioxidant 1010, antioxidant 1024, antioxidant 1035, antioxidant 1330, antioxidant 1076, antioxidant 1098, and antioxidant 3114; the light stabilizer is one or more of light stabilizer 327, light stabilizer 360, light stabilizer 540, light stabilizer 544, light stabilizer 770, light stabilizer 783, light stabilizer 944, and light stabilizer 2020.

[0026] This invention also provides a method for preparing a high-strength, puncture-resistant polyethylene bubble bag, the method comprising the following steps:

[0027] 1) Preparation of outer high-strength polyethylene cross-linked film: High-density polyethylene, metallocene medium-density polyethylene, bimodal high-density polyethylene, compatibilizer, antioxidant and light stabilizer are mixed evenly, extruded and granulated, and dried to obtain a special material for outer high-strength polyethylene cross-linked film; The obtained special material for outer high-strength polyethylene cross-linked film is put into a rotary blown film equipment for processing, and after cooling, it is cut and rolled up to obtain a blown film with a tilted oriented lamellar structure; Two rolls of film are joined together in opposite directions and thermally laminated; after cooling, they are cut and rolled up again to obtain the desired outer high-strength polyethylene cross-linked film with a cross-linked lamellar structure;

[0028] 2) Preparation of inner layer polyethylene heat-sealing film: Take bimodal linear low-density polyethylene, highly branched linear low-density polyethylene, metallocene polyethylene and compatibilizer, stir and mix evenly, extrude and granulate, dry to obtain special material for inner layer polyethylene heat-sealing film; put the obtained special material for inner layer polyethylene heat-sealing film into a rotary blown film equipment for processing, and after cooling, cut and roll up to obtain blown film; take two rolls of film and join them side by side, perform heat lamination, cool and cut and roll up again to obtain the required inner layer polyethylene heat-sealing film;

[0029] 3) Preparation of medium-layer polyethylene cast bubble film: High-density polyethylene, metallocene medium-density polyethylene, bimodal high-density polyethylene, ethylene-octene random copolymer, inorganic filler, organic nucleating agent, compatibilizer, antioxidant, slip agent and light stabilizer are mixed evenly, extruded and granulated to obtain special material for medium-layer polyethylene cast film; The obtained special material for medium-layer polyethylene cast film is fed into a bubble film machine for processing, and the extruded polyethylene is cast, vacuum adsorbed by bubble rollers and compounded into bubble film;

[0030] 4) Preparation of bubble bags: After the bubble film is formed, the outer high-strength polyethylene cross-linked film obtained in step 1) and the inner polyethylene heat-sealing film obtained in step 2) are introduced and laminated with the bubble film through a traction roller. The outer high-strength polyethylene cross-linked film is laminated with the bubble film at the bubble roller, that is, while forming the bubble film, it is pressed together with the outer high-strength polyethylene cross-linked film. The side of the bubble film that forms bubbles is pressed together with the linear low-density polyethylene layer of the inner polyethylene heat-sealing film. After trimming and winding, a high-strength puncture-resistant composite polyethylene bubble film is obtained. The rolled composite polyethylene bubble film is introduced into the bag making machine, and after cutting, bending and hot-pressing the edges, the above-mentioned high-strength puncture-resistant composite polyethylene bubble bag is obtained.

[0031] As a preferred embodiment of the present invention, in step 3), the vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 8-12mm, and the bubble height is 3-7mm.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1) The high-strength composite polyethylene bubble bag prepared by the method of the present invention makes full use of the formulation design and different processing technology to control the crystallization behavior and performance of polyethylene. It has a targeted design of a high-strength, high-toughness, and puncture-resistant outer polyethylene cross-film, a middle bubble film, and a high-strength and high-heat-sealing-strength inner heat-sealing film, which significantly improves the mechanical properties and heat-sealing strength of the bubble film and can be applied to the field of automotive parts packaging and transportation.

[0034] 2) The high-strength, puncture-resistant composite polyethylene bubble bag obtained by the preparation method described in this invention effectively utilizes physical and chemical modifications and process conditions to regulate the crystallization behavior of different polyethylene components, and designs different layers with different structures and properties in a targeted manner to achieve multifunctional requirements, significantly improve the comprehensive mechanical properties of the composite bubble film, meet the "green, environmentally friendly and recyclable" standards for automotive parts packaging, satisfy market requirements, and has high product application value.

[0035] 3) Compared with existing methods, the method described in this invention uses polyethylene material entirely, replacing traditional polypropylene material, and the prepared bubble film can be recycled. By utilizing different formulation designs and specific processing techniques, the compatibility and crystallization behavior of different components can be controlled to improve the mechanical properties and functionality of different composite layers, achieving an organic combination of polyethylene materials with different structures and properties.

[0036] 4) The method for preparing the high-strength, puncture-resistant composite bubble bag of the present invention is simple and efficient, solves the shortcomings of traditional bubble bags that are difficult to recycle and reuse, and provides a feasible solution for the development of related industries of plastic recycling. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] The present invention provides a high-strength, puncture-resistant polyethylene bubble bag, comprising an outer high-strength polyethylene cross-linked film, a middle polyethylene cast bubble film, and an inner polyethylene heat-sealing film, all compositely made.

[0039] The raw materials for the outer high-strength polyethylene cross-linked film include:

[0040] 1) High-density polyethylene (HDPE), 100 parts by weight, the density of HDPE is 0.941-0.965 g / cm³. 3 The melt index is 2.0-4.0 g / 10 min (190℃, 2.16 kg), and the weight-average molecular weight is 200,000-300,000.

[0041] 2) Metallocene medium-density polyethylene (mMDPE), 10-20 parts by weight, the density of which is 0.926-0.930 g / cm³. 3 The melt index is 1.0-2.0 g / 10 min, and the weight-average molecular weight is 100,000-150,000.

[0042] 3) Bimodal high-density polyethylene (BHDPE), 10-20 parts by weight, with a density of 0.945-0.960 g / cm³. 3 The melt index is 1.0-2.0 g / 10 min, the comonomer is 1-butene, 1-hexene or 1-octene, and the ratio of the relative content of high molecular weight peak to the relative content of low molecular weight peak is 1.0-1.4.

[0043] 4) Compatibilizer, 1-3 parts by weight, the compatibilizer is a graft copolymer with glycidyl methacrylate (GMA), butyl acrylate (BA) or maleic anhydride (MA), the grafting rate of GMA, BA and MA in the graft copolymer is 1-1.5%.

[0044] The graft copolymer is one or more of the following: high-density polyethylene grafted with glycidyl methacrylate (HDPE-g-GMA), metallocene medium-density polyethylene grafted with glycidyl methacrylate (mMDPE-g-GMA), bimodal high-density polyethylene grafted with glycidyl methacrylate (BHDPE-g-GMA), high-density polyethylene grafted with butyl acrylate (HDPE-g-BA), metallocene medium-density polyethylene grafted with butyl acrylate (mMDPE-g-BA), bimodal high-density polyethylene grafted with butyl acrylate (BHDPE-g-BA), high-density polyethylene grafted with maleic anhydride (HDPE-g-MA), metallocene medium-density polyethylene grafted with maleic anhydride (mMDPE-g-MA), and bimodal high-density polyethylene grafted with maleic anhydride (BHDPE-g-MA).

[0045] 5) Antioxidant, 0.1-1 parts by weight, wherein the antioxidant is one or more of antioxidant 168, antioxidant 300, antioxidant 330, antioxidant 627A, antioxidant B900, antioxidant 1010, antioxidant 1024, antioxidant 1035, antioxidant 1330, antioxidant 1076, antioxidant 1098 and antioxidant 3114.

[0046] 6) Light stabilizer, 0.1-1 parts by weight, wherein the light stabilizer is one or more of light stabilizer 327, light stabilizer 360, light stabilizer 540, light stabilizer 544, light stabilizer 770, light stabilizer 783, light stabilizer 944, and light stabilizer 2020.

[0047] The raw materials for the middle layer polyethylene cast bubble film include:

[0048] 1) High-density polyethylene (HDPE), 100 parts by weight, the density of HDPE is 0.941-0.965 g / cm³. 3 The melt index is 3.0-5.0 g / 10 min (190℃, 2.16 kg), and the weight-average molecular weight is 200,000-300,000.

[0049] 2) Metallocene medium-density polyethylene (mMDPE), 10-20 parts by weight, the density of which is 0.926-0.930 g / cm³. 3 The melt index is 1.0-2.0 g / 10 min, and the weight-average molecular weight is 100,000-150,000.

[0050] 3) Bimodal high-density polyethylene (BHDPE), 10-20 parts by weight, with a density of 0.945-0.960 g / cm³. 3The melt index is 1.0-2.0 g / 10 min, the comonomer is 1-butene, 1-hexene or 1-octene, and the ratio of the relative content of high molecular weight peak to the relative content of low molecular weight peak is 1.0-1.4.

[0051] 4) Ethylene-octene random copolymer, 5-10 parts by weight, the density of the ethylene-octene random copolymer is 0.870-0.920 g / cm³. 3 The melt index is 2.0-5.0 g / 10 min, the weight-average molecular weight is 150,000-200,000, and the octene content is 20-25%.

[0052] 5) Inorganic filler, 5-10 parts by weight, wherein the inorganic filler is one or more of calcium carbonate, silicon dioxide, talc, titanium dioxide, montmorillonite, kaolin, bentonite, diatomite and barium sulfate, with a particle size of 50-200 nm.

[0053] 6) Organic nucleating agent, 0.1-0.5 parts by weight, wherein the organic nucleating agent is one or more of sorbitol nucleating agents, phosphate nucleating agents and rosin-based nucleating agents.

[0054] The sorbitol nucleating agent is one or more of the following: dibenzyl sorbitol (DBS), p-dimethyl dibenzyl sorbitol (MDBS), di(3,4-dimethyl dibenzyl)sorbitol (DMDBS), di(p-ethyl)benzyl sorbitol (EDBS), di(p-chloro-substituted benzyl)sorbitol (PCIDBS), di(trimethylbenzyl)sorbitol (TMDBS), di(tetrahydronaphthyl)-methylene-sorbitol (DTNHS), p-methylmethylene-sorbitol (MMBS), and di(p-methylbenzyl)-allyl sorbitol (BMBAS).

[0055] The phosphate nucleating agent is one or more of the following: sodium 2,2'-methylene-bis(4-methyl-6-tert-butylphenoxy)phosphate, sodium bis(2,4-di-tert-butylphenoxy)phosphate, sodium bis(2-tert-butyl,4-methylphenoxy)phosphate, and sodium 2,2'-methylene-bis(4,6-di-tert-butylphenoxy)phosphate.

[0056] The rosin-based nucleating agent is one or more of sodium dehydroabirate, potassium dehydroabirate, magnesium dehydroabirate, rosin amide, calcium rosinate, zinc rosinate, and sodium rosinate.

[0057] 7) Compatibilizer, 1-3 parts by weight, wherein the compatibilizer is a graft copolymer with glycidyl methacrylate (GMA), butyl acrylate (BA) or maleic anhydride (MA), wherein the grafting rate of GMA, BA and MA in the graft copolymer is 1-1.5%.

[0058] The graft copolymers mentioned are high-density polyethylene grafted with glycidyl methacrylate (HDPE-g-GMA), metallocene medium-density polyethylene grafted with glycidyl methacrylate (mMDPE-g-GMA), bimodal high-density polyethylene grafted with glycidyl methacrylate (BHDPE-g-GMA), ethylene-octene random copolymer grafted with glycidyl methacrylate (POE-g-GMA), high-density polyethylene grafted with butyl acrylate (HDPE-g-BA), and metallocene medium-density polyethylene grafted with butyl acrylate. One or more of the following: ester (mMDPE-g-BA), bimodal high-density polyethylene grafted with butyl acrylate (BHDPE-g-BA), ethylene-octene random copolymer grafted with butyl acrylate (POE-g-BA), high-density polyethylene grafted with maleic anhydride (HDPE-g-MA), metallocene medium-density polyethylene grafted with maleic anhydride (mMDPE-g-MA), bimodal high-density polyethylene grafted with maleic anhydride (BHDPE-g-MA), and ethylene-octene random copolymer grafted with maleic anhydride (POE-g-MA).

[0059] 8) Slip agent, 0.01-0.2 parts by weight, the slip agent is one or more of the migrating primary amide slip agents such as isostearamide, stearamide, behenamide, oleamide, erucamide, etc.

[0060] 9) Antioxidant, 0.1-1 parts by weight, wherein the antioxidant is one or more of antioxidant 168, antioxidant 300, antioxidant 330, antioxidant 627A, antioxidant B900, antioxidant 1010, antioxidant 1024, antioxidant 1035, antioxidant 1330, antioxidant 1076, antioxidant 1098 and antioxidant 3114.

[0061] 10) Light stabilizer, 0.1-1 parts by weight, wherein the light stabilizer is one or more of light stabilizer 327, light stabilizer 360, light stabilizer 540, light stabilizer 544, light stabilizer 770, light stabilizer 783, light stabilizer 944, and light stabilizer 2020.

[0062] The raw materials for the inner layer polyethylene heat-sealable film include:

[0063] 1) Bimodal linear low-density polyethylene (BLLDPE), 100 parts by weight, the density of bimodal linear low-density polyethylene is 0.910-0.930 g / cm³. 3 The melt index is 2.0-3.0 g / 10 min, the comonomer is 1-butene, 1-hexene or 1-octene, and the ratio of the relative content of the high molecular weight peak to the relative content of the low molecular weight peak is 0.7-0.9.

[0064] 2) Highly branched linear low-density polyethylene (LLDPE), 5-10 parts by weight, with a density of 0.910-0.925 g / cm³. 3 The melt index is 2.0-3.0 g / 10 min, the weight-average molecular weight is 200,000-250,000, and the branching content is 14-17‰.

[0065] 3) Metallocene polyethylene (mPE), 10-20 parts by weight, wherein the metallocene polyethylene is metallocene linear low-density polyethylene (mLLDPE) or metallocene ultra-low-density polyethylene (mVLDPE).

[0066] The metallocene linear low-density polyethylene described has a melt index of 1-2 g / min and a density of 0.910-0.927 g / cm³. 3 The weight-average molecular weight is 150,000-200,000.

[0067] Metallocene ultra-low density polyethylene has a melt index of 1.0-2.0 g / min and a density of 0.900-0.910 g / cm³. 3 The weight-average molecular weight is 150,000-200,000.

[0068] 4) Compatibilizer, 1-3 parts by weight, the compatibilizer is a graft copolymer with glycidyl methacrylate (GMA), butyl acrylate (BA) or maleic anhydride (MA), the grafting rate of GMA, BA and MA in the graft copolymer is 1-1.5%.

[0069] The graft copolymer is one or more of the following: metallocene linear low-density polyethylene grafted with glycidyl methacrylate (mLLDPE-g-GMA), bimodal linear low-density polyethylene grafted with glycidyl methacrylate (BHDPE-g-GMA), linear low-density polyethylene grafted with glycidyl methacrylate (LLDPE-g-GMA), metallocene linear low-density polyethylene grafted with butyl acrylate (mLLDPE-g-BA), bimodal linear low-density polyethylene grafted with butyl acrylate (BHDPE-g-BA), linear low-density polyethylene grafted with butyl acrylate (LLDPE-g-BA), metallocene linear low-density polyethylene grafted with maleic anhydride (mLLDPE-g-MA), bimodal linear low-density polyethylene grafted with maleic anhydride (BHDPE-g-MA), and linear low-density polyethylene grafted with maleic anhydride (LLDPE-g-MA).

[0070] This invention utilizes the circumferential cutting effect of a rotating mold, combined with a high traction ratio, to prepare blown films with tilted-oriented lamellar structures. Specifically, the circumferential cutting stress increases the alignment and growth of crystals in the lateral direction during the growth process, causing the longitudinally aligned lamellars to tilt and deflect laterally. Laterally grown chain segments interpenetrate into other lamellar layers, thereby forming a complete and interconnected network structure, which increases the overall performance of the film and significantly improves its lateral tensile properties.

[0071] Circumferential stress and tensile stress can promote crystallization, form a more perfect crystalline structure, increase crystallinity, and further improve mechanical properties.

[0072] By combining two thin films, a thin film with a cross-laminated crystal structure is obtained, which further improves the tensile strength of the thin film in all directions, and this is used as the outer layer of the bubble film.

[0073] Using high-density polyethylene as the outer film and bubble film matrix, metallocene medium-density polyethylene and bimodal high-density polyethylene are used to improve its mechanical properties, thereby improving its toughness while ensuring high strength, and significantly enhancing its puncture resistance and impact resistance.

[0074] By using compatibilizers to improve compatibility and form a eutectic structure, the mechanical properties of the bubble film are further improved, while the dispersion of processing aids such as antioxidants and light stabilizers within polyethylene is also improved, thereby enhancing antioxidant properties and weather resistance.

[0075] Adding a nucleating agent to bubble film can alter the crystallization behavior of polyethylene, improve nucleation efficiency, reduce the size of spherulites in the film, and improve the mechanical properties of the bubble film.

[0076] Using high-strength and high-toughness bimodal linear low-density polyethylene as the matrix of the heat-sealing film, it has excellent heat-sealing range and heat-sealing performance, and can ensure the mechanical properties such as stiffness of the film. By using a small amount of highly branched linear low-density polyethylene and metallocene polyethylene to control the sealing temperature and heat-sealing strength, a polyethylene heat-sealing film with high strength, high toughness and high heat-sealing strength in all directions can be prepared.

[0077] The inner heat-sealing film also uses rotational blow molding and cross-composite processes to prepare a cross-linked film with good performance in all directions. The two cross-linked films can improve the mechanical properties of the composite bubble film in all directions, especially the mechanical properties perpendicular to the stretching direction (transverse direction).

[0078] Example 1

[0079] This embodiment provides a method for preparing a high-strength, puncture-resistant polyethylene bubble bag, including the following steps:

[0080] I. Preparation of outer high-strength polyethylene cross-linked film:

[0081] 100 parts by weight of a product with a melt index of 2.0 g / 10 min has a density of 0.941 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 200,000 and a melt index of 1.0 g / 10 min has a density of 0.926 g / cm³. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 100,000, and a melt index of 1.0 g / 10 min with a density of 0.945 g / cm³. 3 A mixture of bimodal high-density polyethylene (comonomer 1-butene) with a relative content ratio of 1.0 was prepared. One part by weight of high-density polyethylene grafted with glycidyl methacrylate (grafting rate 1%), 0.1 parts by weight of antioxidant 300, and 0.1 parts by weight of light stabilizer 327 were placed in a mixer and mixed for 20 minutes at room temperature. The mixture was then granulated in a twin-screw extruder with a blending temperature of 180℃, a die temperature of 170℃, and a screw extrusion speed of 100 rpm. After granulation, the mixture was dried in an oven at 60℃ to obtain a special material for high-strength polyethylene cross-linked films with an outer layer.

[0082] The outer layer of polyethylene cross-laminated film is fed into a rotary blown film machine. The processing temperature is set to 175℃, the die temperature to 170℃, the draw ratio to 8, the blow-up ratio to 2.5, and the mandrel speed to 4 rpm. After cooling, the film is cut and wound up to obtain a blown film with a tilted lamellar structure. Then, two rolls of film are joined side to side and thermally laminated. After cooling, they are cut and wound up again to obtain the desired high-strength polyethylene cross-laminated film with a quasi-cross lamellar structure.

[0083] II. Preparation of the inner layer polyethylene cast heat-sealing film:

[0084] Take 100 parts by weight of a product with a melt index of 2.0 g / 10 min and a density of 0.910 g / cm³. 3 The relative content ratio of bimodal linear low-density polyethylene (BLD) is 0.7, and 5 parts by weight of highly branched linear low-density polyethylene (melt index 2.0 g / 10 min, weight-average molecular weight 200,000, density 0.910 g / cm³) is 5 parts by weight. 3 10 parts by weight of metallocene linear low-density polyethylene (melt index 1.0 g / 10 min, weight-average molecular weight 150,000, density 0.910 g / cm³) with a branching content of 14‰. 3One part by weight of metallocene linear low-density polyethylene grafted with glycidyl methacrylate (grafting rate 1%) was placed in a mixer and mixed for 20 min at room temperature at a speed of 200 rpm. The mixture was then granulated in a twin-screw extruder at a blending temperature of 180°C, a die temperature of 170°C, and a screw extrusion speed of 100 rpm. After granulation, the mixture was dried in an oven at 50°C to obtain a special material for inner layer polyethylene heat-sealing film.

[0085] The aforementioned inner layer polyethylene heat-sealing film material is fed into a rotary blown film machine. The processing temperature is set to 175℃, the die temperature to 170℃, the draw ratio to 4, the blow-up ratio to 2.0, and the mandrel speed to 3 rpm. After cooling, the film is cut and wound up to obtain a blown film. Then, two rolls of film are joined together, front and back, and heat-bonded. After cooling, they are cut and wound up again to obtain the required inner layer heat-sealing film.

[0086] III. Preparation of the middle layer bubble film:

[0087] 100 parts by weight of a product with a melt index of 3.0 g / 10 min has a density of 0.941 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 200,000 and a melt index of 1.0 g / 10 min has a density of 0.926 g / cm³. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 100,000, and a melt index of 1.0 g / 10 min with a density of 0.945 g / cm³. 3 The relative content ratio of bimodal high-density polyethylene (comonomer is 1-butene) is 1.0, and 5 parts by weight have a melt index of 2.0 g / 10 min and a density of 0.870 g / cm³. 3 An ethylene-octene random copolymer with a weight average molecular weight of 150,000 (octene content 20%) was used. Then, 5 parts by weight of calcium carbonate, 0.1 parts by weight of dibenzyl sorbitol, 1 part by weight of high-density polyethylene grafted with glycidyl methacrylate (grafting rate 1%), 0.1 parts by weight of antioxidant 168, 0.01 parts by weight of isostearamide, and 0.1 parts by weight of light stabilizer 360 were placed in a mixer and mixed for 20 minutes at room temperature at a speed of 200 rpm. The mixture was then granulated in a twin-screw extruder at a blending temperature of 180℃, a die temperature of 170℃, and a screw extrusion speed of 100 rpm. After granulation, the material was dried in an oven at 50℃ to obtain a special material for middle-layer polyethylene cast film.

[0088] The obtained medium-layer polyethylene cast film material is fed into a bubble film machine. The processing temperature is 190℃ and the speed is set to 200 rpm. The extruded polyethylene is cast, vacuum adsorbed by the bubble roller, and composited into a bubble film. The vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 8mm, and the bubble height is 3mm.

[0089] IV. Preparation of bubble wrap:

[0090] After the bubble wrap has stabilized and formed, the prepared outer high-strength polyethylene cross-linked film and inner polyethylene cast heat-sealing film are introduced into the machine via traction rollers to be laminated with the bubble wrap. The outer high-strength polyethylene cross-linked film is laminated with the bubble wrap at the bubble roll, that is, while forming the bubble wrap, it is pressed together with the outer high-strength polyethylene cross-linked film. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the linear low-density polyethylene layer of the inner polyethylene cast heat-sealing film. After edge trimming and winding, a high-strength, puncture-resistant composite polyethylene bubble wrap is obtained.

[0091] The rolled polyethylene bubble film is fed into the bag making machine, and after steps such as cutting, bending, and hot-pressing to seal the edges, a high-strength, puncture-resistant composite polyethylene bubble bag is obtained. The hot-pressing temperature is 100℃.

[0092] The polyethylene bubble film prepared in this embodiment has a longitudinal tensile strength of 36.7 MPa, a longitudinal elongation at break of 394.5%, a transverse tensile strength of 31.6 MPa, a transverse elongation at break of 426.3%, and a heat seal strength of 19.3 N / 15 mm. The crystallinity of each layer of special material is shown in Table 1. The drop impact breakage mass of the cross-linked film is 2.5 g / μm.

[0093] Example 2

[0094] This embodiment provides a method for preparing a high-strength, puncture-resistant polyethylene bubble bag, including the following steps:

[0095] I. Preparation of outer high-strength polyethylene cross-linked film:

[0096] 100 parts by weight of a product with a melt index of 2.5 g / 10 min has a density of 0.947 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 220,000 and a melt index of 1.2 g / 10 min at 12 parts by weight has a density of 0.927 g / cm³. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 110,000, and a melt index of 1.2 g / 10 min with a density of 0.949 g / cm³. 3A mixture of bimodal high-density polyethylene (comonomer 1-hexene) with a relative content ratio of 1.1 and 1.5 parts by weight of bimodal high-density polyethylene grafted with glycidyl methacrylate (grafting rate 1.1%), 0.3 parts by weight of antioxidant 330, and 0.3 parts by weight of light stabilizer 360 were placed in a mixer and mixed for 20 minutes at room temperature. The mixture was then granulated in a twin-screw extruder with a blending temperature of 182℃, a die temperature of 172℃, and a screw extrusion speed of 125 rpm. After granulation, the granules were dried in an oven at 65℃ to obtain a special material for high-strength polyethylene cross-linked films with an outer layer.

[0097] The outer layer of polyethylene cross-laminated film is fed into a rotary blown film machine. The processing temperature is set to 178℃, the die temperature to 172℃, the draw ratio to 9, the blow-up ratio to 2.8, and the mandrel speed to 4.5 rpm. After cooling, the film is cut and wound up to obtain a blown film with a tilted lamellar structure. Then, two rolls of film are joined side to side and thermally laminated. After cooling, they are cut and wound up again to obtain the desired high-strength polyethylene cross-laminated film with a quasi-cross lamellar structure.

[0098] II. Preparation of the inner layer polyethylene cast heat-sealing film:

[0099] Take 100 parts by weight of a product with a melt index of 2.2 g / 10 min and a density of 0.915 g / cm³. 3 The relative content ratio of bimodal linear low-density polyethylene (BLD) is 0.75, and 6 parts by weight of highly branched linear low-density polyethylene (melt index 2.2 g / 10 min, weight-average molecular weight 210,000, density 0.914 g / cm³) is 6. 3 12 parts by weight of metallocene ultra-low density polyethylene (melt index 1.2 g / 10 min, weight-average molecular weight 160,000, density 0.900 g / cm³) with a branching content of 15‰. 3 1.5 parts by weight of bimodal linear low-density polyethylene grafted with butyl acrylate (grafting rate 1.1%) were placed in a mixer and mixed for 22 minutes at room temperature with a speed of 250 rpm. The mixture was then granulated in a twin-screw extruder with a blending temperature of 182℃, a die temperature of 172℃, and a screw extrusion speed of 125 rpm. After granulation, the material was dried in an oven at 52℃ to obtain a special material for inner layer polyethylene heat-sealing film.

[0100] The aforementioned inner layer polyethylene heat-sealing film material is fed into a rotary blown film machine. The processing temperature is set to 177℃, the die temperature to 177℃, the draw ratio to 5, the blow-up ratio to 2.2, and the mandrel speed to 3.5 rpm. After cooling, the film is cut and wound up to obtain a blown film. Then, two rolls of film are joined side to side and heat-bonded. After cooling, they are cut and wound up again to obtain the required inner layer heat-sealing film.

[0101] III. Preparation of the middle layer bubble film:

[0102] 100 parts by weight of a product with a melt index of 3.5 g / 10 min has a density of 0.947 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 220,000 and a melt index of 1.2 g / 10 min at 12 parts by weight has a density of 0.927 g / cm³. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 110,000, and a melt index of 1.2 g / 10 min with a density of 0.949 g / cm³. 3 The relative content ratio of bimodal high-density polyethylene (comonomer is 1-butene) is 1.1, and 6 parts by weight have a melt index of 2.8 g / 10 min and a density of 0.880 g / cm³. 3 An ethylene-octene random copolymer with a weight average molecular weight of 160,000 (octene content 21%) was used. Then, 6 parts by weight of silica, 0.2 parts by weight of p-methylmethylene sorbitol, 1.5 parts by weight of bimodal high-density polyethylene grafted with glycidyl methacrylate (grafting rate 1-1.1%), 0.3 parts by weight of antioxidant 300, 0.05 parts by weight of stearamide, and 0.3 parts by weight of light stabilizer 540 were placed in a mixer and mixed for 22 minutes at room temperature at a speed of 250 rpm. The mixture was then granulated in a twin-screw extruder at a blending temperature of 182℃, a die temperature of 172℃, and a screw extrusion speed of 125 rpm. After granulation, the material was dried in an oven at 52℃ to obtain a special material for middle-layer polyethylene cast film.

[0103] The obtained medium-layer polyethylene cast film material is fed into a bubble film machine. The processing temperature is 195℃ and the speed is set to 250 rpm. The extruded polyethylene is cast, vacuum adsorbed by the bubble roller, and composited into a bubble film. The vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 9mm, and the bubble height is 4mm.

[0104] IV. Preparation of bubble wrap:

[0105] After the bubble wrap has stabilized and formed, the prepared outer high-strength polyethylene cross-linked film and inner polyethylene cast heat-sealing film are introduced into the machine via traction rollers to be laminated with the bubble wrap. The outer high-strength polyethylene cross-linked film is laminated with the bubble wrap at the bubble roll, that is, while forming the bubble wrap, it is pressed together with the outer high-strength polyethylene cross-linked film. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the linear low-density polyethylene layer of the inner polyethylene cast heat-sealing film. After edge trimming and winding, a high-strength, puncture-resistant composite polyethylene bubble wrap is obtained.

[0106] Finally, the rolled polyethylene bubble film is introduced into the bag making machine, and after steps such as cutting, bending, and hot-pressing to seal the edges, a high-strength, puncture-resistant composite polyethylene bubble bag is obtained. The hot-pressing temperature is 102℃.

[0107] The polyethylene bubble film prepared in this embodiment has a longitudinal tensile strength of 37.1 MPa, a longitudinal elongation at break of 376.7%, a transverse tensile strength of 33.4 MPa, a transverse elongation at break of 401.8%, and a heat seal strength of 20.4 N / 15 mm. The crystallinity of each layer of special material is shown in Table 1. The drop impact breakage mass of the cross-linked film is 2.8 g / μm.

[0108] Example 3

[0109] This embodiment provides a method for preparing a high-strength, puncture-resistant polyethylene bubble bag, including the following steps:

[0110] I. Preparation of outer high-strength polyethylene cross-linked film:

[0111] Take 100 parts by weight of material with a melt index of 3.0 g / 10 min and a density of 0.953 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 250,000, and a melt index of 1.5 g / 10 min with a density of 0.928 g / cm³, is used. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 120,000, and a melt index of 1.5 g / 10 min with a density of 0.953 g / cm³. 3 A mixture of bimodal high-density polyethylene (HDPE) with a relative content ratio of 12 (comonomer being 1-octene), 1 part by weight of bimodal HDPE grafted with butyl acrylate (grafting rate 1.3%), HDPE grafted with maleic anhydride (grafting rate 1.3%), 0.3 parts by weight of antioxidant 168, 0.3 parts by weight of antioxidant 1035, 0.3 parts by weight of light stabilizer 360, and 0.3 parts by weight of light stabilizer 783 was placed in a mixer and mixed for 25 minutes at room temperature. The mixture was then granulated in a twin-screw extruder with a blending temperature of 185℃, a die temperature of 175℃, and a screw extrusion speed of 150 rpm. After granulation, the material was dried in an oven at 70℃ to obtain a special material for high-strength polyethylene cross-linked films with an outer layer.

[0112] The outer layer of polyethylene cross-laminated film is fed into a rotary blown film machine. The processing temperature is set to 180℃, the die temperature to 175℃, the draw ratio to 10, the blow-up ratio to 3.0, and the mandrel speed to 5 rpm. After cooling, the film is cut and wound up to obtain a blown film with a tilted lamellar structure. Then, two rolls of film are joined side to side and thermally laminated. After cooling, they are cut and wound up again to obtain the desired high-strength polyethylene cross-laminated film with a quasi-cross lamellar structure.

[0113] II. Preparation of the inner layer polyethylene cast heat-sealing film:

[0114] Take 100 parts by weight of a product with a melt index of 2.5 g / 10 min and a density of 0.920 g / cm³. 3 The relative content ratio of bimodal linear low-density polyethylene (BLD) was 0.8, and 8 parts by weight of highly branched linear low-density polyethylene (melt index 2.5 g / 10 min, weight-average molecular weight 220,000, density 0.918 g / cm³) was also present. 3 15 parts by weight of metallocene linear low-density polyethylene (melt index 1.5 g / 10 min, weight-average molecular weight 180,000, density 0.918 g / cm³) with a branching content of 15.5‰. 3 0.8 parts by weight of bimodal linear low-density polyethylene grafted with butyl acrylate (grafting rate 1.3%) and 0.8 parts by weight of metallocene linear low-density polyethylene grafted with maleic anhydride (grafting rate 1.3%) were placed in a mixer and mixed at room temperature for 25 minutes at a speed of 300 rpm. The mixture was then granulated in a twin-screw extruder at a blending temperature of 185℃, a die temperature of 175℃, and a screw extrusion speed of 150 rpm. After granulation, the material was dried in an oven at 55℃ to obtain a special material for inner layer polyethylene heat-sealing film.

[0115] The aforementioned inner layer polyethylene heat-sealing film material is fed into a rotary blown film machine. The processing temperature is set to 180℃, the die temperature to 175℃, the draw ratio to 6, the blow-up ratio to 2.5, and the mandrel speed to 4 rpm. After cooling, the film is cut and wound up to obtain a blown film. Then, two rolls of film are joined together, front and back, and heat-bonded. After cooling, they are cut and wound up again to obtain the required inner layer heat-sealing film.

[0116] III. Preparation of the middle layer bubble film:

[0117] Take 100 parts by weight of material with a melt index of 4.0 g / 10 min and a density of 0.953 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 250,000, and a melt index of 1.2 g / 10 min with a density of 0.928 g / cm³, is used. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 130,000, and a melt index of 1.5 g / 10 min with a density of 0.953 g / cm³. 3 The relative content ratio of bimodal high-density polyethylene (comonomer is 1-hexene) is 1.2, and 8 parts by weight have a melt index of 3.6 g / 10 min and a density of 0.890 g / cm³. 3The following ingredients were added: ethylene-octene random copolymer with a weight average molecular weight of 180,000 (octene content 23%); 3 parts by weight of talc; 4 parts by weight of calcium carbonate; 0.1 parts by weight of sodium 2,2'-methylene-bis(4-methyl-6-tert-butylphenoxy)phosphate; 0.3 parts by weight of sodium dehydroabietic acid; 0.8 parts by weight of ethylene-octene random copolymer grafted with glycidyl methacrylate (grafting rate 1.3%); 0.8 parts by weight of high-density polyethylene grafted with butyl acrylate (grafting rate 1.3%); and 0.3 parts by weight of... Antioxidant 300 (parts by weight), antioxidant 1035 (0.3 parts by weight), stearamide (0.05 parts by weight), behenamide (0.3 parts by weight), light stabilizer 770 (0.3 parts by weight), and light stabilizer 2020 (parts by weight) were placed in a mixer and mixed for 25 minutes at room temperature at a speed of 300 rpm. The mixture was then granulated in a twin-screw extruder at a blending temperature of 185°C, a die temperature of 175°C, and a screw extrusion speed of 150 rpm. After granulation, the mixture was dried in an oven at 55°C to obtain a special material for middle-layer polyethylene cast film.

[0118] The obtained medium-layer polyethylene cast film material is fed into a bubble film machine. The processing temperature is 200℃ and the speed is set to 300 rpm. The extruded polyethylene is cast, vacuum adsorbed by the bubble roller, and composited into a bubble film. The vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 10mm, and the bubble height is 5mm.

[0119] IV. Preparation of bubble wrap:

[0120] After the bubble wrap has stabilized and formed, the prepared outer high-strength polyethylene cross-linked film and inner polyethylene cast heat-sealing film are introduced into the machine via traction rollers to be laminated with the bubble wrap. The outer high-strength polyethylene cross-linked film is laminated with the bubble wrap at the bubble roll, that is, while forming the bubble wrap, it is pressed together with the outer high-strength polyethylene cross-linked film. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the linear low-density polyethylene layer of the inner polyethylene cast heat-sealing film. After edge trimming and winding, a high-strength, puncture-resistant composite polyethylene bubble wrap is obtained.

[0121] Finally, the rolled polyethylene bubble film is introduced into the bag making machine, and after steps such as cutting, bending, and hot-pressing to seal the edges, a high-strength, puncture-resistant composite polyethylene bubble bag is obtained. The hot-pressing temperature is 103℃.

[0122] The polyethylene bubble film prepared in this embodiment has a longitudinal tensile strength of 38.3 MPa, a longitudinal elongation at break of 353.5%, a transverse tensile strength of 35.9 MPa, a transverse elongation at break of 397.3%, and a heat seal strength of 20.9 N / 15 mm. The crystallinity of each layer of special material is shown in Table 1. The drop impact breakage mass of the cross-linked film is 3.0 g / μm.

[0123] Example 4

[0124] This embodiment provides a method for preparing a high-strength, puncture-resistant polyethylene bubble bag, including the following steps:

[0125] I. Preparation of outer high-strength polyethylene cross-linked film:

[0126] Take 100 parts by weight of material with a melt index of 3.5 g / 10 min and a density of 0.959 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 270,000, and a melt index of 1.7 g / 10 min with a density of 0.929 g / cm³, was obtained from 18 parts by weight. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 140,000, and a melt index of 1.7 g / 10 min with a density of 0.957 g / cm³. 3 A mixture of bimodal high-density polyethylene (comonomer 1-butene) with a relative content ratio of 1.3, and 1.3 parts by weight of metallocene medium-density polyethylene grafted with glycidyl methacrylate (grafting rate 1.4%), 1.3 parts by weight of bimodal high-density polyethylene grafted with butyl acrylate (grafting rate 1.4%), 0.4 parts by weight of antioxidant 627A, 0.4 parts by weight of antioxidant 1330, 0.4 parts by weight of light stabilizer 770, and 0.4 parts by weight of light stabilizer 944 were placed in a mixer and mixed for 27 minutes at room temperature. The mixture was then granulated in a twin-screw extruder with a blending temperature of 187℃, a die temperature of 177℃, and a screw extrusion speed of 175 rpm. After granulation, the material was dried in an oven at 75℃ to obtain a special material for high-strength polyethylene cross-linked films with an outer layer.

[0127] The outer layer of polyethylene cross-laminated film is fed into a rotary blown film machine. The processing temperature is set to 182℃, the die temperature to 177℃, the draw ratio to 12, the blow-up ratio to 3.3, and the mandrel speed to 5.5 rpm. After cooling, the film is cut and wound up to obtain a blown film with a tilted lamellar structure. Then, two rolls of film are joined side to side and thermally laminated. After cooling, they are cut and wound up again to obtain the desired high-strength polyethylene cross-laminated film with a quasi-cross lamellar structure.

[0128] II. Preparation of the inner layer polyethylene cast heat-sealing film:

[0129] Take 100 parts by weight of a product with a melt index of 2.7 g / 10 min and a density of 0.925 g / cm³. 3 The relative content ratio of bimodal linear low-density polyethylene (BLD) is 0.85, and 8 parts by weight of highly branched linear low-density polyethylene (melt index 2.7 g / 10 min, weight-average molecular weight 240,000, density 0.922 g / cm³) is 8.3 The product contains 18 parts by weight of metallocene ultra-low density polyethylene (melt index 1.80 g / 10 min, weight-average molecular weight 180,000, density 0.907 g / cm³), with a branching content of 16‰. 3 1.3 parts by weight of bimodal linear low-density polyethylene grafted with glycidyl methacrylate (grafting rate 1.4%) and 1.3 parts by weight of metallocene linear low-density polyethylene grafted with butyl acrylate (grafting rate 1.4%) were placed in a mixer and mixed for 27 minutes at room temperature at a speed of 350 rpm. The mixture was then granulated in a twin-screw extruder at a blending temperature of 187°C, a die temperature of 177°C, and a screw extrusion speed of 175 rpm. After granulation, the granules were dried in an oven at 57°C to obtain a special material for inner layer polyethylene heat-sealing film.

[0130] The aforementioned inner layer polyethylene heat-sealing film material is fed into a rotary blown film machine. The processing temperature is set to 182℃, the die temperature to 178℃, the draw ratio to 7, the blow-up ratio to 2.8, and the mandrel speed to 4.5 rpm. After cooling, the film is cut and wound up to obtain a blown film. Then, two rolls of film are joined side to side and heat-bonded. After cooling, they are cut and wound up again to obtain the required inner layer heat-sealing film.

[0131] III. Preparation of the middle layer bubble film:

[0132] Take 100 parts by weight of material with a melt index of 4.5 g / 10 min and a density of 0.959 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 270,000, and a melt index of 1.7 g / 10 min with a density of 0.929 g / cm³, was obtained from 18 parts by weight. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 140,000, and a melt index of 1.8 g / 10 min with a density of 0.957 g / cm³. 3 The relative content ratio of bimodal high-density polyethylene (comonomer is 1-octene) is 1.3, and 8 parts by weight have a melt index of 4.2 g / 10 min and a density of 0.910 g / cm³. 3The following components were used: an ethylene-octene random copolymer with a weight-average molecular weight of 190,000 (octene content 24%); 4 parts by weight of titanium dioxide; 4 parts by weight of montmorillonite; 0.2 parts by weight of di(3,4-dimethyldibenzyl)sorbitol; 0.2 parts by weight of magnesium dehydroabirate; 1.3 parts by weight of metallocene medium-density polyethylene grafted with butyl acrylate (grafting rate 1.3%); 1.2 parts by weight of bimodal high-density polyethylene grafted with maleic anhydride (grafting rate 1.4%); and 0.5 parts by weight of antioxidant 1. 0.35 parts by weight of antioxidant 1330, 0.08 parts by weight of behenamide, 0.08 parts by weight of oleamide, 0.5 parts by weight of light stabilizer 783, and 0.5 parts by weight of light stabilizer 944 were placed in a mixer and mixed for 27 minutes at room temperature with a speed of 350 rpm. The mixed material was then granulated in a twin-screw extruder with a blending temperature of 187°C, a die temperature of 177°C, and a screw extrusion speed of 175 rpm. After granulation, the material was dried in an oven at 57°C to obtain a special material for medium-layer polyethylene cast film.

[0133] The obtained medium-layer polyethylene cast film material is fed into a bubble film machine. The processing temperature is 205℃ and the speed is set to 350 rpm. The extruded polyethylene is cast, vacuum adsorbed by the bubble roller, and composited into a bubble film. The vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 11mm, and the bubble height is 6mm.

[0134] IV. Preparation of bubble wrap:

[0135] After the bubble wrap has stabilized and formed, the prepared outer high-strength polyethylene cross-linked film and inner polyethylene cast heat-sealing film are introduced into the machine via traction rollers to be laminated with the bubble wrap. The outer high-strength polyethylene cross-linked film is laminated with the bubble wrap at the bubble roll, that is, while forming the bubble wrap, it is pressed together with the outer high-strength polyethylene cross-linked film. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the linear low-density polyethylene layer of the inner polyethylene cast heat-sealing film. After edge trimming and winding, a high-strength, puncture-resistant composite polyethylene bubble wrap is obtained.

[0136] Finally, the rolled polyethylene bubble film is introduced into the bag making machine, and after steps such as cutting, bending, and hot-pressing to seal the edges, a high-strength, puncture-resistant composite polyethylene bubble bag is obtained. The hot-pressing temperature is 104℃.

[0137] The polyethylene bubble film prepared in this embodiment has a longitudinal tensile strength of 39.6 MPa, a longitudinal elongation at break of 328.7%, a transverse tensile strength of 38.2 MPa, a transverse elongation at break of 354.6%, and a heat seal strength of 21.6 N / 15 mm. The crystallinity of each layer of special material is shown in Table 1. The drop impact breakage mass of the cross-linked film is 3.2 g / μm.

[0138] Example 5

[0139] This embodiment provides a method for preparing a high-strength, puncture-resistant polyethylene bubble bag, including the following steps:

[0140] I. Preparation of outer high-strength polyethylene cross-linked film:

[0141] Take 50 parts by weight of a product with a melt index of 4.0 g / 10 min and a density of 0.944 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 300,000 and a melt index of 3.0 g / 10 min at 50 parts by weight has a density of 0.965 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 250,000 and a melt index of 2.0 g / 10 min has a density of 0.926 g / cm³. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 150,000, and a melt index of 1.0 g / 10 min with a density of 0.930 g / cm³. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 150,000, and a melt index of 2.0 g / 10 min with a density of 0.945 g / cm³. 3 The relative content ratio of bimodal high-density polyethylene (comonomer is 1-butene) is 1.4, and the density of 10 parts by weight is 0.960 g / cm³ with a melt index of 1.5 g / 10 min. 3 A mixture of bimodal high-density polyethylene (comonomer 1-octene) with a relative content ratio of 1.3 and 1 part by weight of metallocene medium-density polyethylene grafted with butyl acrylate (grafting rate 1.5%), 1 part by weight of bimodal high-density polyethylene grafted with butyl acrylate (grafting rate 1.3%), 1 part by weight of high-density polyethylene grafted with maleic anhydride (grafting rate 1.5%), 0.5 parts by weight of antioxidant 1024, 0.5 parts by weight of antioxidant 1098, 0.3 parts by weight of light stabilizer 770, 0.3 parts by weight of light stabilizer 783, and 0.4 parts by weight of light stabilizer 944 was placed in a mixer and mixed for 30 minutes at room temperature. The mixture was then granulated in a twin-screw extruder with a blending temperature of 190℃, a die temperature of 180℃, and a screw extrusion speed of 200 rpm. After granulation, the mixture was dried in an oven at 80℃ to obtain a special material for high-strength polyethylene cross-linked films with an outer layer.

[0142] The outer layer of polyethylene cross-laminated film is fed into a rotary blown film machine. The processing temperature is set to 185℃, the die temperature to 180℃, the draw ratio to 13, the blow-up ratio to 3.5, and the mandrel speed to 6 rpm. After cooling, the film is cut and wound up to obtain a blown film with a tilted lamellar structure. Then, two rolls of film are joined side to side and thermally laminated. After cooling, they are cut and wound up again to obtain the desired high-strength polyethylene cross-laminated film with a cross-laminated structure.

[0143] II. Preparation of the inner layer polyethylene cast heat-sealing film:

[0144] Take 50 parts by weight of a product with a melt index of 2.0 g / 10 min and a density of 0.910 g / cm³. 3 The relative content ratio of bimodal linear low-density polyethylene is 0.8, with a melt index of 2.5 g / 10 min and a density of 0.930 g / cm³ at 50 parts by weight. 3 The relative content ratio of bimodal linear low-density polyethylene (BLD) is 0.9, and 5 parts by weight of highly branched linear low-density polyethylene (melt index 3.0 g / 10 min, weight-average molecular weight 250,000, density 0.910 g / cm³) is 5 parts by weight. 3 5 parts by weight of highly branched linear low-density polyethylene (melt index 2.0 g / 10 min, weight-average molecular weight 220,000, density 0.925 g / cm³) with a branching content of 17‰. 3 10 parts by weight of metallocene linear low-density polyethylene (melt index 2.0 g / 10 min, weight-average molecular weight 200,000, density 0.927 g / cm³) with a branching content of 16‰. 3 10 parts by weight of metallocene ultra-low density polyethylene (melt index 1.5 g / 10 min, weight-average molecular weight 180,000, density 0.910 g / cm³) 3 One part by weight each of metallocene linear low-density polyethylene grafted with butyl acrylate (grafting rate 1.5%), bimodal linear low-density polyethylene grafted with butyl acrylate (grafting rate 1.4%), and linear low-density polyethylene grafted with butyl acrylate (grafting rate 1.5%) was placed in a mixer and mixed for 30 minutes at room temperature with a speed of 400 rpm. The mixture was then granulated in a twin-screw extruder with a blending temperature of 190℃, a die temperature of 180℃, and a screw extrusion speed of 200 rpm. After granulation, the granules were dried in an oven at 60℃ to obtain a special material for inner layer polyethylene heat-sealing film.

[0145] The aforementioned inner layer polyethylene heat-sealing film material is fed into a rotary blown film machine. The processing temperature is set to 185℃, the die temperature to 180℃, the draw ratio to 8, the blow-up ratio to 3.0, and the mandrel speed to 5 rpm. After cooling, the film is cut and wound up to obtain a blown film. Then, two rolls of film are joined side to side and heat-bonded. After cooling, they are cut and wound up again to obtain the required inner layer heat-sealing film.

[0146] III. Preparation of the middle layer bubble film:

[0147] Take 50 parts by weight of a product with a melt index of 5.0 g / 10 min and a density of 0.941 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 300,000 and a melt index of 4.0 g / 10 min at 50 parts by weight has a density of 0.965 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 280,000 and a melt index of 2.0 g / 10 min has a density of 0.926 g / cm³. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 150,000, and a melt index of 1.8 g / 10 min and a density of 0.930 g / cm³. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 140,000, and a melt index of 2.0 g / 10 min with a density of 0.945 g / cm³. 3 The relative content ratio of bimodal high-density polyethylene (comonomer is 1-butene) is 1.4, and the density of 10 parts by weight is 0.960 g / cm³ with a melt index of 1.8 g / 10 min. 3 The relative content ratio of bimodal high-density polyethylene (comonomer is 1-hexene) is 1.4, and 5 parts by weight have a melt index of 5.0 g / 10 min and a density of 0.870 g / cm³. 3 The ethylene-octene random copolymer (octene content 25%) with a weight average molecular weight of 200,000 and a melt index of 4.5 g / 10 min has a density of 0.920 g / cm³. 3The following components were used: an ethylene-octene random copolymer with a weight-average molecular weight of 190,000 (octene content 23%); 3 parts by weight of bentonite; 3 parts by weight of diatomaceous earth; 4 parts by weight of barium sulfate; 0.2 parts by weight of bis(tetrahydronaphthylene)sorbitol; 0.2 parts by weight of sodium bis(2,4-di-tert-butylphenoxy)phosphate; 0.1 parts by weight of rosin amide; 1 part by weight of metallocene medium-density polyethylene grafted with glycidyl methacrylate (grafting rate 1.5%); 1 part by weight of high-density polyethylene grafted with butyl acrylate (grafting rate 1.3%); and 1 part by weight of bimodal high-density polyethylene grafted with maleic anhydride (grafting rate 1.3%). 1.4% (parts by weight), 0.5 parts by weight of antioxidant 1098, 0.5 parts by weight of antioxidant 3114, 0.1 parts by weight of erucamide, 0.1 parts by weight of erucamide, 0.1 parts by weight of isostearamide, 0.3 parts by weight of light stabilizer 327, 0.3 parts by weight of light stabilizer 783, and 0.4 parts by weight of light stabilizer 944 were placed in a mixer and mixed at room temperature for 30 minutes at a speed of 400 rpm. The mixed material was then granulated in a twin-screw extruder at a blending temperature of 190°C, a die temperature of 180°C, and a screw extrusion speed of 200 rpm. After granulation, the material was dried in an oven at 60°C to obtain a special material for medium-layer polyethylene cast film.

[0148] The obtained medium-layer polyethylene cast film material is fed into a bubble film machine. The processing temperature is 210℃ and the speed is set to 400 rpm. The extruded polyethylene is cast, vacuum adsorbed by the bubble roller, and composited into a bubble film. The vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 12mm, and the bubble height is 7mm.

[0149] IV. Preparation of bubble wrap:

[0150] After the bubble wrap has stabilized and formed, the prepared outer high-strength polyethylene cross-linked film and inner polyethylene cast heat-sealing film are introduced into the machine via traction rollers to be laminated with the bubble wrap. The outer high-strength polyethylene cross-linked film is laminated with the bubble wrap at the bubble roll, that is, while forming the bubble wrap, it is pressed together with the outer high-strength polyethylene cross-linked film. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the linear low-density polyethylene layer of the inner polyethylene cast heat-sealing film. After edge trimming and winding, a high-strength, puncture-resistant composite polyethylene bubble wrap is obtained.

[0151] Finally, the rolled polyethylene bubble film is introduced into the bag making machine, and after steps such as cutting, bending, and hot-pressing to seal the edges, a high-strength, puncture-resistant composite polyethylene bubble bag is obtained. The hot-pressing temperature is 105℃.

[0152] The polyethylene bubble film prepared in this embodiment has a longitudinal tensile strength of 41.2 MPa, a longitudinal elongation at break of 314.1%, a transverse tensile strength of 38.5 MPa, a transverse elongation at break of 335.8%, a heat seal strength of 22.8 N / 15 mm, and crystallinity of each layer of special material as shown in Table 1. The drop impact breakage mass of the cross-linked film is 3.5 g / μm.

[0153] Comparative Example 1

[0154] Bubble film preparation:

[0155] 100 parts by weight of a product with a melt index of 3.0 g / 10 min has a density of 0.941 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 200,000 and a melt index of 1.0 g / 10 min has a density of 0.926 g / cm³. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 100,000, and a melt index of 1.0 g / 10 min with a density of 0.945 g / cm³. 3 The relative content ratio of bimodal high-density polyethylene (comonomer is 1-butene) is 1.0, and 5 parts by weight have a melt index of 2.0 g / 10 min and a density of 0.870 g / cm³. 3 An ethylene-octene random copolymer with a weight average molecular weight of 150,000 (octene content 20%) was prepared. Then, 5 parts by weight of calcium carbonate, 0.1 parts by weight of dibenzyl sorbitol, 1 part by weight of high-density polyethylene grafted with glycidyl methacrylate (grafting rate 1%), 0.1 parts by weight of antioxidant 168, 0.01 parts by weight of isostearamide, and 0.1 parts by weight of light stabilizer 360 were placed in a mixer and mixed for 20 minutes at room temperature at a speed of 200 rpm. The mixture was then granulated in a twin-screw extruder at a blending temperature of 180℃, a die temperature of 170℃, and a screw extrusion speed of 100 rpm. After granulation, the material was dried in an oven at 50℃ to obtain a special material for polyethylene cast film.

[0156] The obtained polyethylene cast film material is fed into a bubble film machine. The processing temperature is 190℃ and the speed is set to 200 rpm. The extruded polyethylene is cast, vacuum adsorbed by the bubble roller, and composited into a bubble film. The vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 8mm, and the bubble height is 3mm.

[0157] Finally, the rolled polyethylene bubble film is introduced into the bag making machine, and after steps such as cutting, bending, and hot-pressing to seal the edges, a high-strength, puncture-resistant composite polyethylene bubble bag is obtained. The hot-pressing temperature is 100℃.

[0158] The polyethylene bubble film was tested and found to have a longitudinal tensile strength of 33.2 MPa, a longitudinal elongation at break of 426.2%, a transverse tensile strength of 28.6 MPa, a transverse elongation at break of 453.5%, and a heat-sealing strength of 10.3 N / 15 mm. The crystallinity of each layer of the special material is shown in Table 1.

[0159] Comparative Example 2

[0160] Preparation of outer high-strength polyethylene cross-linked film:

[0161] 100 parts by weight of a product with a melt index of 2.0 g / 10 min has a density of 0.941 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 200,000 and a melt index of 1.0 g / 10 min has a density of 0.926 g / cm³. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 100,000, and a melt index of 1.0 g / 10 min with a density of 0.945 g / cm³. 3 A mixture of bimodal high-density polyethylene (comonomer 1-butene) with a relative content ratio of 1.0 was prepared. One part by weight of high-density polyethylene grafted with glycidyl methacrylate (grafting rate 1%), 0.1 parts by weight of antioxidant 300, and 0.1 parts by weight of light stabilizer 327 were placed in a mixer and mixed for 20 minutes at room temperature. The mixture was then granulated in a twin-screw extruder with a blending temperature of 180℃, a die temperature of 170℃, and a screw extrusion speed of 100 rpm. After granulation, the mixture was dried in an oven at 60℃ to obtain a special material for high-strength polyethylene cross-linked films with an outer layer.

[0162] The outer layer of polyethylene cross-laminated film is fed into a rotary blown film machine. The processing temperature is set to 175℃, the die temperature to 170℃, the draw ratio to 8, the blow-up ratio to 2.5, and the mandrel speed to 4 rpm. After cooling, the film is cut and wound up to obtain a blown film with a tilted lamellar structure. Then, two rolls of film are joined side to side and thermally laminated. After cooling, they are cut and wound up again to obtain the desired high-strength polyethylene cross-laminated film with a quasi-cross lamellar structure.

[0163] Preparation of the middle layer bubble film:

[0164] 100 parts by weight of a product with a melt index of 3.0 g / 10 min has a density of 0.941 g / cm³. 3 The high-density polyethylene with a weight-average molecular weight of 200,000 and a melt index of 1.0 g / 10 min has a density of 0.926 g / cm³. 3 Metallocene medium-density polyethylene with a weight-average molecular weight of 100,000, and a melt index of 1.0 g / 10 min with a density of 0.945 g / cm³.3 The relative content ratio of bimodal high-density polyethylene (comonomer is 1-butene) is 1.0, and 5 parts by weight have a melt index of 2.0 g / 10 min and a density of 0.870 g / cm³. 3 An ethylene-octene random copolymer with a weight average molecular weight of 150,000 (octene content 20%) was used. Then, 5 parts by weight of calcium carbonate, 0.1 parts by weight of dibenzyl sorbitol, 1 part by weight of high-density polyethylene grafted with glycidyl methacrylate (grafting rate 1%), 0.1 parts by weight of antioxidant 168, 0.01 parts by weight of isostearamide, and 0.1 parts by weight of light stabilizer 360 were placed in a mixer and mixed for 20 minutes at room temperature at a speed of 200 rpm. The mixture was then granulated in a twin-screw extruder at a blending temperature of 180℃, a die temperature of 170℃, and a screw extrusion speed of 100 rpm. After granulation, the material was dried in an oven at 50℃ to obtain a special material for middle-layer polyethylene cast film.

[0165] The obtained medium-layer polyethylene cast film material is fed into a bubble film machine. The processing temperature is 190℃ and the speed is set to 200 rpm. The extruded polyethylene is cast, vacuum adsorbed by the bubble roller, and composited into a bubble film. The vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 8mm, and the bubble height is 3mm.

[0166] Preparation of bubble wrap:

[0167] After the bubble wrap has stabilized and formed, the prepared outer high-strength polyethylene cross-linked film is introduced into the machine via a traction roller to laminate with the bubble wrap. The outer high-strength polyethylene cross-linked film is laminated with the bubble wrap on the bubble wrap roller, meaning that while the bubble wrap is forming, it is pressed together with the outer high-strength polyethylene cross-linked film. After edge trimming and winding, the composite polyethylene bubble wrap is obtained.

[0168] Finally, the rolled polyethylene bubble film is introduced into the bag making machine, and after steps such as cutting, bending, and hot-pressing to seal the edges, a high-strength, puncture-resistant composite polyethylene bubble bag is obtained. The hot-pressing temperature is 100℃.

[0169] The polyethylene bubble film was tested and found to have a longitudinal tensile strength of 37.5 MPa, a longitudinal elongation at break of 384.7%, a transverse tensile strength of 30.9 MPa, a transverse elongation at break of 441.3%, a heat seal strength of 9.6 N / 15 mm, and crystallinity of each layer of special material as shown in Table 1. The drop impact breakage mass of the cross-linked film was 2.5 g / μm.

[0170] Comparative Example 3

[0171] Preparation of outer high-strength polyethylene cross-linked film:

[0172] 100 parts by weight of a product with a melt index of 2.0 g / 10 min has a density of 0.941 g / cm³. 3 0.1 parts by weight of antioxidant 300 and 0.1 parts by weight of light stabilizer 327 of high-density polyethylene with a weight average molecular weight of 200,000 were placed in a mixer and mixed for 20 minutes at room temperature. The mixture was then granulated in a twin-screw extruder with a blending temperature of 180°C, a die temperature of 170°C, and a screw extrusion speed of 100 rpm. After granulation, the material was dried in an oven at 60°C to obtain a special material for high-strength polyethylene cross-linked films with an outer layer.

[0173] The outer layer of polyethylene cross-laminated film is fed into a rotary blown film machine. The processing temperature is set to 175℃, the die temperature to 170℃, the draw ratio to 8, the blow-up ratio to 2.5, and the mandrel speed to 4 rpm. After cooling, the film is cut and wound up to obtain a blown film with a tilted lamellar structure. Then, two rolls of film are joined side to side and thermally laminated. After cooling, they are cut and wound up again to obtain the desired high-strength polyethylene cross-laminated film with a quasi-cross lamellar structure.

[0174] Preparation of inner layer polyethylene cast heat-sealing film:

[0175] Take 100 parts by weight of a product with a melt index of 1.0 g / 10 min and a density of 0.945 g / cm³. 3 Bimodal high-density polyethylene with a relative content ratio of 1.0 is fed into a rotary blown film machine. The processing temperature is set at 175℃, the die temperature at 170℃, the draw ratio at 4, the blow-up ratio at 2.0, and the mandrel speed at 3 rpm. After cooling, the film is cut and wound up to obtain a blown film. Then, two rolls of film are joined side to side for heat lamination. After cooling, they are cut and wound up again to obtain the required inner heat-sealing film.

[0176] Preparation of the middle layer bubble film:

[0177] 100 parts by weight of a product with a melt index of 3.0 g / 10 min has a density of 0.941 g / cm³. 3 High-density polyethylene with a weight average molecular weight of 200,000, 5 parts by weight of calcium carbonate, 0.1 parts by weight of dibenzyl sorbitol, 1 part by weight of high-density polyethylene grafted with glycidyl methacrylate (grafting rate of 1%), 0.1 parts by weight of antioxidant 168, 0.01 parts by weight of isostearamide, and 0.1 parts by weight of light stabilizer 360 were placed in a mixer and mixed for 20 minutes at room temperature with a speed of 200 rpm. The mixture was then granulated in a twin-screw extruder with a blending temperature of 180℃, a die temperature of 170℃, and a screw extrusion speed of 100 rpm. After granulation, the material was dried in an oven at 50℃ to obtain a special material for middle-layer polyethylene cast film.

[0178] The obtained medium-layer polyethylene cast film material is fed into a bubble film machine. The processing temperature is 190℃ and the speed is set to 200 rpm. The extruded polyethylene is cast, vacuum adsorbed by the bubble roller, and composited into a bubble film. The vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 8mm, and the bubble height is 3mm.

[0179] Preparation of bubble wrap:

[0180] After the bubble wrap has stabilized and formed, the prepared outer high-strength polyethylene cross-linked film and inner polyethylene cast heat-sealing film are introduced into the machine via traction rollers to laminate with the bubble wrap. The outer high-strength polyethylene cross-linked film is laminated with the bubble wrap on the bubble roll, meaning that while forming the bubble wrap, it is pressed together with the outer high-strength polyethylene cross-linked film. Immediately afterwards, the side of the bubble wrap with the formed bubbles is pressed together with the inner polyethylene cast heat-sealing film. After edge trimming and winding, the composite polyethylene bubble wrap is obtained.

[0181] Finally, the rolled polyethylene bubble film is introduced into the bag making machine, and after steps such as cutting, bending, and hot-pressing to seal the edges, a high-strength, puncture-resistant composite polyethylene bubble bag is obtained. The hot-pressing temperature is 100℃.

[0182] The polyethylene bubble film was tested and found to have a longitudinal tensile strength of 38.5 MPa, a longitudinal elongation at break of 285.9%, a transverse tensile strength of 35.6 MPa, a transverse elongation at break of 299.3%, a heat seal strength of 12.1 N / 15 mm, and crystallinity of each layer of special material as shown in Table 1. The drop impact breakage mass of the cross-linked film was 1.1 g / μm.

[0183] Comparative Example 4

[0184] The preparation methods of the outer polyethylene cross-linked film, inner polyethylene heat-sealing film, middle bubble film, and bubble bag in this comparative example are the same as those in Example 1, except that the mandrel rotation speed is adjusted to 0 rpm, i.e., the mandrel rotation is turned off.

[0185] The polyethylene bubble film was tested and found to have a longitudinal tensile strength of 35.5 MPa, a longitudinal elongation at break of 385.9%, a transverse tensile strength of 29.6 MPa, a transverse elongation at break of 411.4%, a heat seal strength of 19.8 N / 15 mm, and crystallinity of each layer of special material as shown in Table 1. The drop impact breakage mass of the cross-linked film was 2.3 g / μm.

[0186] Table 1 Crystallinity of each layer of polyethylene bubble film

[0187] Example 1 48.2 37.9 Example 2 49.6 39.1 Example 3 50.1 39.9 Example 4 50.7 40.3 Example 5 51.2 40.7 Comparative Example 1 / 37.9 Comparative Example 2 48.2 37.9 Comparative Example 3 49.0 38.6 Comparative Example 4 43.9 37.9

[0188] It is evident that the high-strength, puncture-resistant composite polyethylene bubble wrap obtained by the preparation method described in this invention effectively utilizes physical and chemical modifications and process conditions to regulate the crystallization behavior of different polyethylene components, and designs different layers with different structures and properties in a targeted manner to achieve multifunctional requirements. This significantly improves the comprehensive mechanical properties of the composite bubble wrap, meets the "green, environmentally friendly, and recyclable" standards for automotive parts packaging, satisfies market requirements, and has high product application value.

[0189] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high-strength, puncture-resistant polyethylene bubble bag, characterized in that, The product comprises a composite outer layer of high-strength polyethylene cross-linked film, a middle layer of polyethylene cast bubble film, and an inner layer of polyethylene heat-sealable film. The raw materials for the outer high-strength polyethylene cross-linked film include: high-density polyethylene, metallocene medium-density polyethylene, bimodal high-density polyethylene, compatibilizers, antioxidants, and light stabilizers. The raw materials for the middle layer of polyethylene cast bubble film include: high-density polyethylene, metallocene medium-density polyethylene, bimodal high-density polyethylene, ethylene-octene random copolymer, inorganic fillers, organic nucleating agents, compatibilizers, slip agents, antioxidants, and light stabilizers. The raw materials for the inner polyethylene heat-sealable film include: bimodal linear low-density polyethylene, highly branched linear low-density polyethylene, metallocene polyethylene, and compatibilizers. Preparation of outer high-strength polyethylene cross-linked film: High-density polyethylene, metallocene medium-density polyethylene, bimodal high-density polyethylene, compatibilizer, antioxidant and light stabilizer are mixed evenly, extruded and granulated, and dried to obtain a special material for outer high-strength polyethylene cross-linked film; The obtained special material for outer high-strength polyethylene cross-linked film is fed into a rotary blown film equipment for processing, and after cooling, it is cut and rolled up to obtain a blown film with a tilted oriented lamellar structure; Two rolls of film are joined together, thermally laminated, cooled, and then cut and rolled up again to obtain the desired outer high-strength polyethylene cross-linked film with a cross-linked lamellar structure; The density of the bimodal linear low-density polyethylene is 0.910-0.930 g / cm³. 3 The melt index is 2.0-3.0 g / 10 min, and the ratio of the relative content of high molecular weight peaks to the relative content of low molecular weight peaks is 0.7-0.

9. The density of the highly branched linear low-density polyethylene is 0.910-0.925 g / cm³. 3 The melt index is 2.0-3.0 g / 10min, the weight-average molecular weight is 200,000-250,000, and the branching content is 14-17‰. The metallocene polyethylene is metallocene linear low-density polyethylene or metallocene ultra-low-density polyethylene; The metallocene linear low-density polyethylene described has a melt index of 1.0-2.0 g / 10 min and a density of 0.910-0.927 g / cm³. 3 The weight-average molecular weight is 150,000-200,000; The metallocene ultra-low density polyethylene described has a melt index of 1.0-2.0 g / 10 min and a density of 0.900-0.910 g / cm³. 3 The weight-average molecular weight is 150,000-200,000.

2. The high-strength, puncture-resistant polyethylene bubble bag according to claim 1, characterized in that, By weight, the raw materials for the outer high-strength polyethylene cross-linked film are: 100 parts high-density polyethylene, 10-20 parts metallocene medium-density polyethylene, 10-20 parts bimodal high-density polyethylene, 1-3 parts compatibilizer, 0.1-1 parts antioxidant and 0.1-1 parts light stabilizer.

3. The high-strength, puncture-resistant polyethylene bubble bag according to claim 1, characterized in that, By weight, the raw materials for the middle layer polyethylene cast bubble film are: 100 parts high-density polyethylene, 10-20 parts metallocene medium-density polyethylene, 10-20 parts bimodal high-density polyethylene, 5-10 parts ethylene-octene random copolymer, 5-10 parts inorganic filler, 0.1-0.5 parts organic nucleating agent, 1-3 parts compatibilizer, 0.01-0.2 parts slip agent, 0.1-1 parts antioxidant and 0.1-1 parts light stabilizer.

4. A high-strength, puncture-resistant polyethylene bubble bag according to claim 1, characterized in that, By weight, the raw materials for the inner layer polyethylene heat-sealing film are: 100 parts bimodal linear low-density polyethylene, 5-10 parts highly branched linear low-density polyethylene, 10-20 parts metallocene polyethylene and 1-3 parts compatibilizer.

5. A high-strength, puncture-resistant polyethylene bubble bag according to any one of claims 1-4, characterized in that, The density of the high-density polyethylene is 0.941-0.965 g / cm³. 3 The melt index is 2.0-4.0 g / 10 min, and the weight-average molecular weight is 200,000-300,000. The density of the metallocene medium-density polyethylene is 0.926-0.930 g / cm³. 3 The melt index is 1.0-2.0 g / 10 min, and the weight-average molecular weight is 100,000-150,000. The density of the bimodal high-density polyethylene is 0.945-0.960 g / cm³. 3 The melt index is 1.0-2.0 g / 10 min, and the ratio of the relative content of high molecular weight peak to the relative content of low molecular weight peak is 1.0-1.

4.

6. A high-strength, puncture-resistant polyethylene bubble bag according to any one of claims 1-4, characterized in that, The density of the ethylene-octene random copolymer is 0.870-0.920 g / cm³. 3 The melt flow index is 2.0-5.0 g / 10 min, the weight-average molecular weight is 150,000-200,000, and the octene content is 20-25%; the inorganic filler is one or more of calcium carbonate, silicon dioxide, talc, titanium dioxide, montmorillonite, kaolin, bentonite, diatomaceous earth, and barium sulfate, with a particle size of 50-200 nm; the organic nucleating agent is one or more of sorbitol nucleating agents, phosphate nucleating agents, and rosin-based nucleating agents; the slip agent is one or more of isostearamide, stearamide, behenamide, oleamide, and erucamide; the compatibilizer is a graft copolymer with glycidyl methacrylate, butyl acrylate, or maleic anhydride, with a grafting rate of 1-1.5%.

7. A high-strength, puncture-resistant polyethylene bubble bag according to any one of claims 1-4, characterized in that, The antioxidant is one or more of antioxidant 168, antioxidant 300, antioxidant 330, antioxidant 627A, antioxidant B900, antioxidant 1010, antioxidant 1024, antioxidant 1035, antioxidant 1330, antioxidant 1076, antioxidant 1098, and antioxidant 3114; the light stabilizer is one or more of light stabilizer 327, light stabilizer 360, light stabilizer 540, light stabilizer 544, light stabilizer 770, light stabilizer 783, light stabilizer 944, and light stabilizer 2020.

8. A method for preparing a high-strength, puncture-resistant polyethylene bubble bag, characterized in that, The preparation method includes the following steps: 1) Preparation of outer high-strength polyethylene cross-linked film: High-density polyethylene, metallocene medium-density polyethylene, bimodal high-density polyethylene, compatibilizer, antioxidant and light stabilizer are mixed evenly, extruded and granulated, and dried to obtain a special material for outer high-strength polyethylene cross-linked film; The obtained special material for outer high-strength polyethylene cross-linked film is put into a rotary blown film equipment for processing, and after cooling, it is cut and rolled up to obtain a blown film with a tilted oriented lamellar structure; Two rolls of film are joined together, thermally laminated, cooled and then cut and rolled up again to obtain the desired outer high-strength polyethylene cross-linked film with a cross-linked lamellar structure; 2) Preparation of inner layer polyethylene heat-sealing film: Take bimodal linear low-density polyethylene, highly branched linear low-density polyethylene, metallocene polyethylene and compatibilizer, stir and mix evenly, extrude and granulate, dry to obtain special material for inner layer polyethylene heat-sealing film; put the obtained special material for inner layer polyethylene heat-sealing film into a rotary blown film equipment for processing, and after cooling, cut and roll up to obtain blown film; take two rolls of film and join them side by side, perform heat lamination, cool and cut and roll up again to obtain the required inner layer polyethylene heat-sealing film; 3) Preparation of medium-layer polyethylene cast bubble film: High-density polyethylene, metallocene medium-density polyethylene, bimodal high-density polyethylene, ethylene-octene random copolymer, inorganic filler, organic nucleating agent, compatibilizer, antioxidant, slip agent and light stabilizer are mixed evenly, extruded and granulated to obtain special material for medium-layer polyethylene cast film; The obtained special material for medium-layer polyethylene cast film is fed into a bubble film machine for processing, and the extruded polyethylene is cast, vacuum adsorbed by bubble rollers and compounded into bubble film; 4) Preparation of bubble bags: After the bubble film is formed, the outer high-strength polyethylene cross-linked film obtained in step 1) and the inner polyethylene heat-sealing film obtained in step 2) are introduced and composited with the bubble film through a traction roller. The outer high-strength polyethylene cross-linked film is composited with the bubble film at the bubble roller, that is, while forming the bubble film, it is pressed together with the outer high-strength polyethylene cross-linked film. The side of the bubble film that forms the bubble is pressed together with the linear low-density polyethylene layer of the inner polyethylene heat-sealing film. After edge trimming and winding, a high-strength puncture-resistant composite polyethylene bubble film is obtained. The rolled composite polyethylene bubble film is introduced into a bag making machine, and after cutting, bending and hot-pressing the edges, the high-strength puncture-resistant polyethylene bubble bag as described in any one of claims 1-7 is obtained.

9. The method for preparing a high-strength, puncture-resistant polyethylene bubble bag according to claim 8, characterized in that, In step 3), the vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 8-12mm, and the bubble height is 3-7mm.