Recyclable polyethylene bubble bag and method for producing the same

Abstract

The application discloses a recyclable polyethylene bubble bag and a preparation method thereof, and adopts physical and chemical blending technologies of different polyethylenes and copolymers thereof, effectively combines different molecular chain structures of polyethylene materials, forms molecular diffusion and entanglement between two components at the interface, and improves the interface bonding strength of different layers. Meanwhile, through the design of the melting temperature of different layers, the melting temperature of each layer is adjusted by using different polyethylene-alpha-polyolefin elastomers, the outer layer polyethylene material with a higher melting point, the middle layer and the inner layer polyethylene material with a lower melting point are obtained, the melting point of the outer layer and the inner layer polyethylene is differentiated, the effective compounding and heat sealing of the multilayer film are realized without using hot melt pressure sensitive adhesive, and the mechanical properties and heat sealing strength of different composite layers are improved. The recyclable polyethylene bubble bag using polyethylene material is obtained by solving the bag making technology of the multilayer composite polyethylene bubble film without hot melt pressure sensitive adhesive.

Description

Technical Field

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

[0002] In recent years, with increasingly fierce market competition, major global automakers have reformed their supply systems, implementing global production and procurement strategies. This has ultimately led to the separation of automotive parts manufacturing from vehicle manufacturing, allowing them to face the market independently. Consequently, the demand for automotive parts packaging materials has increased dramatically. The use of packaging materials can significantly reduce the breakage rate of automotive parts and meet transportation requirements. However, traditional bubble wrap is mainly made of various materials such as polyethylene and polypropylene. Due to the high degree of incompatibility in physical and processing properties, different materials cannot be processed using a unified recycling process to produce recycled materials. Furthermore, the difficulty in separating the layers makes them unrecyclable, often resulting in direct disposal after use, causing serious environmental harm. Since 2015, global plastic waste production has continued to increase, exceeding 300 million tons annually. Faced with the increasingly severe global plastic pollution crisis, creating a closed-loop system for plastics through recycling and reuse, improving the level of plastic resource recycling, and shifting from a linear economy to a sustainable green circular economy have become an inevitable trend. This has led to the proposal of comprehensive governance of plastic pollution across the entire chain, strengthening the classification, recycling, and reuse of plastic waste, and planning for the vigorous development of a circular economy, including plastic recycling, to address prominent contradictions and problems, achieve efficient and circular utilization of plastics, and promote high-quality economic and social development. Therefore, the development of recyclable polyethylene bubble wrap is imperative.

[0003] Patent CN107936345A modifies polyethylene to improve the mechanical strength of bubble film, but the modification method is complex and cumbersome, with a long reaction cycle and low production efficiency, making it unsuitable for large-scale production and promotion.

[0004] Patent CN112208178A uses polypropylene to increase the stiffness of polyethylene film to prepare a three-layer co-extruded film that is composited with bubble film. This method uses a large amount of polypropylene and its copolymers. The material after being composited with bubble film is difficult to recycle and reuse. Moreover, it does not take into account the problems of film and bubble film composite and heat sealing.

[0005] Patent CN108177409A uses different polyethylene materials to prepare a five-layer co-extruded heat-shrink film. By adjusting the content of different types of polyethylene in each layer, the toughness of the heat-shrink film is increased in a synergistic way. However, this method does not take into account the composite strength between the layers and is not suitable for the production of bubble wrap.

[0006] Patent CN 108359170 A uses low-density polyethylene, linear low-density polyethylene and elastomer to prepare polyethylene film to prepare co-extruded film. It uses low-temperature elastomer as low-temperature heat-sealing layer to reduce the heat-sealing temperature of polyethylene film. However, this method does not take into account the bonding strength between the layers and the film stiffness is insufficient, making it unsuitable for the production of bubble film.

[0007] Traditional bubble wrap uses polypropylene for the outer layer and polyethylene for the middle and inner layers. The middle layer is made of polyethylene through casting, vacuum forming, and lamination, while the inner layer is a polyethylene blown film. Polypropylene is used for the outer layer because its melting point is higher than polyethylene's. This difference in melting points ensures effective heat sealing of the inner layer without damaging the outer layer. However, the main problem with polypropylene is its poor compatibility with polyethylene. Hot-melt pressure-sensitive adhesive is often used during heat sealing to maintain the inner layer's heat seal strength. This makes the recycled bubble wrap difficult to peel off, significantly increasing the recycling challenge.

[0008] Furthermore, the physical and processing properties of polyethylene and polypropylene are highly mismatched, making it impossible to use a unified recycling process to prepare recycled materials. Moreover, the polyethylene and polypropylene layers are difficult to separate, which increases the difficulty of recycling and often results in them being directly discarded after use, causing serious harm to the environment.

[0009] Therefore, developing bubble bags made entirely of polyethylene material can enable recycling. Summary of the Invention

[0010] To address the aforementioned problems, this invention provides a recyclable polyethylene bubble bag and its preparation method. This invention employs physical and chemical blending techniques using different polyethylene materials and their copolymers. Through the effective combination of different molecular chain structures in the polyethylene materials, molecular diffusion and entanglement are formed between the two components at the interface, improving the interfacial bonding strength between different layers. Simultaneously, by designing the melting temperatures of different layers and utilizing different polyethylene-α-polyolefin elastomers to adjust the melting temperature of each layer, an outer polyethylene material with a higher melting point and middle and inner polyethylene materials with lower melting points are obtained. Through the difference in melting points between the outer and inner polyethylene layers, effective composite and heat-sealing of multi-layer films are achieved without the use of hot-melt pressure-sensitive adhesive, improving the mechanical properties and heat-sealing strength of different composite layers. This overcomes the challenge of hot-melt pressure-sensitive adhesive-free bag-making technology for multi-layer composite polyethylene bubble films, resulting in recyclable polyethylene bubble bags made entirely of polyethylene materials.

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

[0012] This invention first provides a recyclable polyethylene bubble bag, which comprises, in sequence, an outer polyethylene blown film, a middle polyethylene cast bubble film, and an inner polyethylene blown film. The raw materials of the outer polyethylene blown film, by weight, include: 100 parts of high-density polyethylene (HDPE), 2-10 parts of metallocene linear low-density polyethylene (mLLDPE), 10-20 parts of a first toughening agent, 0.04-0.1 parts of a whitening agent, 2-4 parts of an antistatic agent, and 0.1-2 parts of a flame retardant.

[0013] The raw materials of the middle layer polyethylene cast bubble film, by weight, include: 100 parts of low-density polyethylene (LDPE), 10-30 parts of a second toughening agent, 10-20 parts of metallocene linear low-density polyethylene, 0.04-0.1 parts of a whitening agent, 0.1-0.4 parts of a first opening agent, 0.01-0.2 parts of a slip agent, 2-4 parts of an antistatic agent, and 0.1-2 parts of a flame retardant;

[0014] The raw materials of the inner polyethylene blown film, by weight, include: 100 parts of linear low-density polyethylene (LLDPE), 10-20 parts of metallocene linear low-density polyethylene, 10-30 parts of a second toughening agent, 0.1-0.4 parts of a second opening agent, 0.01-0.2 parts of a slip agent, 2-4 parts of an antistatic agent, and 0.1-2 parts of a flame retardant.

[0015] In this invention, the branched entanglement of metallocene linear low-density polyethylene (mLLDPE) and polyalphaolefin elastomer is utilized to form molecular diffusion and entanglement between the two components at the interface, thereby improving the interfacial bonding strength between different layers, and the polyalphaolefin elastomer is used for toughening modification.

[0016] By adjusting the melting temperature of the polyethylene layer using ethylene-α-olefin random copolymer (POE) and ethylene-α-olefin block copolymer (OBC), the difference in melting points between the inner and outer polyethylene layers is increased, thereby achieving effective composite and heat sealing of multilayer films.

[0017] This invention uses only polyethylene and its copolymers, and the bubble bags can be recycled after use.

[0018] In a preferred embodiment of the present invention, the high-density polyethylene in the raw material of the outer polyethylene blown film has a density of 0.941-0.965 g / cm³. 3 The melt flow index is 2.0-3.0 g / 10 min, and the first toughening agent is an ethylene-α-olefin block copolymer.

[0019] As an example, the first toughening agent used in this invention can be one or more of ethylene-octene block copolymers of 9000, 9010, 9007, 9077, 9100, and 9107. However, the first toughening agent used is not limited to other grades of OBC materials.

[0020] In a preferred embodiment of the present invention, the low-density polyethylene in the raw material of the middle-layer polyethylene cast bubble film has a density of 0.910-0.925 g / cm³. 3 The first toughening agent is a low-temperature elastomer obtained by random copolymerization of ethylene with 1-butene or 1-octene, with a melt index of 4.0-5.0 g / 10 min and a melting point of 55-80 °C.

[0021] As an example, in this invention, the second toughening agent used can be one or more of ethylene-1 octene random copolymers such as 8200, 8411, and 8452, and ethylene-1 butene random copolymers such as 7256, DF8200, and A4085s. However, the second toughening agent used is not limited to other grades of POE materials.

[0022] In a preferred embodiment of the present invention, the linear low-density polyethylene in the raw material of the inner polyethylene blown film has a density of 0.910-0.925 g / cm³. 3 The melt flow index is 2.0-3.0 g / 10 min.

[0023] In a preferred embodiment of the present invention, the metallocene linear low-density polyethylene is a linear low-density polyethylene obtained by metallocene-catalyzed copolymerization of ethylene and higher olefins, with a melt index of 2-5 g / min and a density of 0.910-0.927 g / cm³. 3 .

[0024] As a preferred embodiment of the present invention, the metallocene linear low-density polyethylene is one or more of 2718CB, 3518CB, 3518GA, and 4518PA metallocene linear low-density polyethylene.

[0025] Of course, the metallocene linear low-density polyethylene of the present invention is not limited to the above-mentioned grade of mLLDPE, and other grades of mLLDPE can also be used.

[0026] In a preferred embodiment of the present invention, the whitening agent is one or more of 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, stilbene bisbenzoxazole, 1,4-bis(benzoxazolyl-2-yl)naphthalene, 4,4-bis(5-methyl-2-benzoxazolyl)stilbene, and 1,4-bis(5-methyl-2-benzoxazolyl)naphthalene;

[0027] The antistatic agent is one or more of the following: polyol fatty acid esters, fatty acid alkanolamides, fatty amine ethoxy ethers, and phosphate fatty alcohol esters.

[0028] The flame retardant is one or more of chlorinated paraffin, antimony trioxide, aluminum hydroxide, and magnesium hydroxide;

[0029] The first opening agent of the middle layer polyethylene cast film is one or more of barium sulfate, silicon dioxide, calcium sulfate, dicalcium phosphate and diatomaceous earth, and the particle size of the opening agent is 50-200nm.

[0030] The second opening agent of the inner polyethylene blow molding is one or more of talc, hydrated magnesium silicate, diatomaceous earth, molecular sieve and calcium carbonate, and the particle size of the opening agent is 50-200nm.

[0031] The slip agent is one or more of the following migratory primary amide slip agents: peroleamide, erucamide, behenamide, stearamide, and isostearamide.

[0032] The present invention also provides a method for preparing the above-mentioned recyclable polyethylene bubble bag, the method comprising the following steps:

[0033] 1) Preparation of the outer polyethylene film:

[0034] According to the formula, high-density polyethylene, metallocene linear low-density polyethylene, first toughening agent, whitening agent, antistatic agent and flame retardant are placed in a mixer, and the mixed material is granulated in a twin-screw extruder; after granulation, it is dried to obtain a special material for outer polyethylene film blow molding; the special material for outer polyethylene film blow molding is fed into a blown film machine, and after molding, it is cooled by an air ring. After cooling, it is rotated and pulled, cut and wound to obtain the outer polyethylene film;

[0035] 2) Preparation of the inner polyethylene film:

[0036] According to the formula, linear low-density polyethylene, metallocene linear low-density polyethylene, second toughening agent, second opening agent, slip agent, antistatic agent and flame retardant are placed in a mixer, and the mixed material is granulated in a twin-screw extruder; after granulation, it is dried to obtain a special material for inner layer polyethylene film blow molding; the special material for inner layer polyethylene film blow molding is fed into a blown film machine, and after molding, it is cooled by an air ring. After cooling, it is rotated and pulled, cut and wound to obtain the inner layer polyethylene film;

[0037] 3) Preparation of the middle layer bubble film:

[0038] According to the formula, low-density polyethylene, second toughening agent, metallocene linear low-density polyethylene, whitening agent, first opening agent, slip agent, antistatic agent and flame retardant are placed in a mixer, and the mixed material is granulated in a twin-screw extruder; after granulation, it is dried to obtain a 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, and the extruded polyethylene is cast, vacuum adsorbed by bubble rollers, and compounded into bubble film;

[0039] 4) After the bubble film obtained in step 3) has stabilized and formed, the outer polyethylene film prepared in step 1) and the inner polyethylene film prepared in step 2) are introduced into the machine through the traction roller to be laminated with the bubble film; the outer polyethylene 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 polyethylene film. Then, the side of the bubble film that forms the bubble is pressed together with the inner polyethylene film. After cutting the edges and winding, a recyclable polyethylene bubble film is obtained. Finally, the rolled polyethylene bubble film is introduced into the bag making machine, and after cutting, bending, hot pressing and sealing, a recyclable polyethylene bubble bag is obtained. The hot pressing temperature is 90-95℃.

[0040] In a preferred embodiment of the present invention, in step 1), the conditions for mixing in the mixer are: mixing at room temperature for 20-30 minutes and a rotation speed of 200-400 rpm; the conditions for twin-screw extrusion are: blending temperature of 185-195℃, die temperature of 170-180℃, screw extrusion speed of 100-200 rpm, and drying temperature after granulation of 60-80℃; the processing temperature for blown film is 180-190℃, and the blow-up ratio is 1.5-2.8; and the traction ratio for rotary traction is 3.0-4.5.

[0041] In step 2), the mixing conditions are as follows: mixing at room temperature for 20-30 minutes and a rotation speed of 200-400 rpm; the twin-screw extrusion conditions are: blending temperature of 160-170℃, die temperature of 150-160℃, screw extrusion speed of 100-200 rpm, and drying temperature after granulation of 50-60℃; the processing temperature during blown film extrusion is 160-170℃ and the blow-up ratio is 2.0-3.0; and the traction ratio during rotary traction is 3.5-4.5.

[0042] As a preferred embodiment of the present invention, in step 3), the mixer is mixed at room temperature for 20-30 minutes at a speed of 200-400 rpm; the twin-screw extrusion conditions are a blending temperature of 170-180℃, a die temperature of 160-170℃, a screw extrusion speed of 100-200 rpm, and a drying temperature of 50-60℃ after granulation.

[0043] The processing temperature in the bubble wrap machine is 190-200℃, and the rotation speed is 300-500 rpm; the vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 8-12mm, and the bubble height is 3-7mm.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1) The method of the present invention is used to prepare recyclable polyethylene bubble bags, which 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.

[0046] 2) The recyclable polyethylene bubble bags obtained by the preparation method described in this invention have high molecular entanglement and interlayer interface bonding force, excellent comprehensive mechanical properties, and can be recycled and reused, resulting in high product application value.

[0047] 3) Compared with existing methods, the method described in this invention uses polyethylene material entirely, replacing traditional polypropylene material. It utilizes the entanglement of different polyethylene material molecular structures to improve interlayer composite strength. Furthermore, it uses different polyα-olefin elastomers to adjust the melting temperature of each layer, improving heat-sealing strength and achieving heat-melt-free pressure-sensitive adhesive bag-making technology.

[0048] 4) The method for preparing recyclable bubble bags described in this invention is simple and efficient, solves the "plastic pollution" problem caused by traditional bubble bags, and provides a feasible solution for the development of related industries of plastic recycling. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the polyethylene bubble film composite of the present invention.

[0050] In the diagram, A is the outer polyethylene film; B is the middle polyethylene bubble film; and C is the inner polyethylene film. Detailed Implementation

[0051] 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.

[0052] In this invention, all raw materials, reagents, or equipment used can be purchased from the market.

[0053] The method for preparing recyclable polyethylene bubble bags provided by this invention includes the following technical solutions:

[0054] Preparation of outer polyethylene film:

[0055] First, 100 parts by weight of high-density polyethylene, 2-10 parts by weight of metallocene linear low-density polyethylene, 10-20 parts by weight of the first toughening agent, 0.04-0.1 parts by weight of the whitening agent, 2-4 parts by weight of the antistatic agent, and 0.1-2 parts by weight of the flame retardant are placed in a mixer and mixed at room temperature for 20-30 minutes at a speed of 200-400 rpm. Then, the mixed material is granulated in a twin-screw extruder at a blending temperature of 185-195℃, a die temperature of 170-180℃, and a screw extrusion speed of 100-200 rpm. After granulation, the material is dried in an oven at 60-80℃ to obtain a special material for outer polyethylene film blow molding.

[0056] The outer polyethylene film is fed into a blown film machine. The processing temperature is set to 180-190℃ and the blow-up ratio is 1.5-2.8. After molding, the film is cooled by an air ring and then rotated and pulled with a pull ratio of 3.0-4.5. Finally, the film is cut and wound up to obtain the outer polyethylene film.

[0057] Preparation of the inner polyethylene film:

[0058] First, 100 parts by weight of linear low-density polyethylene, 10-20 parts by weight of metallocene linear low-density polyethylene, 10-30 parts by weight of a second toughening agent, 0.1-0.4 parts by weight of a second opening agent, 0.01-0.2 parts by weight of a slip agent, 2-4 parts by weight of an antistatic agent, and 0.1-2 parts by weight of a flame retardant are placed in a mixer and mixed at room temperature for 20-30 minutes at a speed of 200-400 rpm. Then, the mixed material is granulated in a twin-screw extruder at a blending temperature of 160-170℃, a die temperature of 150-160℃, and a screw extrusion speed of 100-200 rpm. After granulation, the material is dried in an oven at 50-60℃ to obtain a special material for outer polyethylene film blow molding.

[0059] The inner polyethylene film blowing material is fed into the blown film machine, the processing temperature is set to 160-170℃, the blow-up ratio is 2.0-3.0, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a pull ratio of 3.5-4.5. Then it is cut and rolled up to obtain the inner polyethylene film.

[0060] Preparation of the middle layer bubble film:

[0061] First, 100 parts by weight of low-density polyethylene, 10-30 parts by weight of a second toughening agent, 10-20 parts by weight of metallocene linear low-density polyethylene, 0.04-0.1 parts by weight of a whitening agent, 0.1-0.4 parts by weight of a first opening agent, 0.01-0.2 parts by weight of a slip agent, 2-4 parts by weight of an antistatic agent, and 0.1-2 parts by weight of a flame retardant are placed in a mixer and mixed at room temperature for 20-30 minutes at a speed of 200-400 rpm. Then, the mixed material is granulated in a twin-screw extruder at a blending temperature of 170-180℃, a die temperature of 160-170℃, and a screw extrusion speed of 100-200 rpm. After granulation, the material is dried in an oven at 50-60℃ to obtain a special material for medium-layer polyethylene cast film.

[0062] The obtained medium-layer polyethylene cast film material is fed into a bubble film machine. The processing temperature is 190-200℃, and the rotation speed is set to 300-500 rpm. The extruded polyethylene is cast, vacuum-adsorbed by a bubble roller, and laminated into a bubble film. The vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 8-12mm, and the bubble height is 3-7mm. The lamination process of the recyclable polyethylene bubble film described in the patent is as follows: Figure 1 As shown.

[0063] Preparation of bubble wrap:

[0064] After the bubble wrap has stabilized and formed, the prepared outer and inner polyethylene films are introduced into the machine via traction rollers to laminate with the bubble wrap. The outer polyethylene film is laminated with the bubble wrap roller during bubble wrap formation, meaning that the outer polyethylene film is pressed together with the bubble wrap while the bubble is forming. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the inner polyethylene film. After edge trimming and winding, recyclable polyethylene bubble wrap is obtained. (The lamination process is as follows...) Figure 1 (As shown)

[0065] 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 recyclable polyethylene bubble bag is obtained. The hot-pressing temperature is 90-95℃.

[0066] Performance Evaluation

[0067] 1. Melting point test:

[0068] Approximately 5 mg of sample was taken from the special materials of the inner blown film, the middle bubble film, and the outer blown film. Its crystallization and melting behavior was determined using a DSC differential scanning calorimeter. Under a nitrogen atmosphere, a "heat-descent-heat" mode was used, with a heating and cooling rate of 10 °C / min, and repeated scanning was performed in the temperature range of 20-190 °C to obtain the melting point of the material.

[0069] 2. Tensile test:

[0070] In accordance with the relevant provisions of the standard "QB1259-1991-Polyethylene Air Cushion Film", the prepared recyclable polyethylene bubble film was subjected to tensile testing to test its tensile strength and elongation at break.

[0071] Example 1

[0072] This embodiment provides a method for preparing recyclable polyethylene bubble bags, including:

[0073] Preparation of outer polyethylene film:

[0074] First, 100 parts by weight of high-density polyethylene, 2 parts by weight of 2718CB metallocene linear low-density polyethylene, 10 parts by weight of 9000 ethylene-octene block copolymer, 0.04 parts by weight of 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, 2 parts by weight of polyol fatty acid ester, and 0.1 parts by weight of chlorinated paraffin were placed in a mixer and mixed for 20 minutes at room temperature with a speed of 200 rpm. Then, the mixed material was granulated in a twin-screw extruder with a blending temperature of 185℃, a die temperature of 170℃, and a screw extrusion speed of 100 rpm. After granulation, the material was dried in an oven at 60℃ to obtain a special material for outer polyethylene film blow molding.

[0075] The outer polyethylene film blowing material is fed into the blown film machine, the processing temperature is set to 180℃, the blow-up ratio is 1.5, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a traction ratio of 3.0. Then it is cut and rolled up to obtain the outer polyethylene film.

[0076] Preparation of the inner polyethylene film:

[0077] First, 100 parts by weight of linear low-density polyethylene, 10 parts by weight of 2718 metallocene linear low-density polyethylene, 10 parts by weight of 8200 ethylene-1-octene random copolymer, 0.1 parts by weight of talc, 0.01 parts by weight of oleamide, 2 parts by weight of polyol fatty acid ester, and 0.1 parts by weight of chlorinated paraffin were placed in a mixer and mixed for 20 minutes at room temperature with a speed of 200 rpm. Then, the mixed material was granulated in a twin-screw extruder with a blending temperature of 160℃, a die temperature of 150℃, 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 inner layer polyethylene film blow molding.

[0078] The inner polyethylene film blowing material is fed into the blown film machine, the processing temperature is set to 160℃, the blow-up ratio is 2.0, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a pull ratio of 3.5. Then it is cut and rolled up to obtain the inner polyethylene film.

[0079] Preparation of the middle layer bubble film:

[0080] First, 100 parts by weight of low-density polyethylene, 10 parts by weight of 8200 ethylene-1-octene copolymer, 10 parts by weight of 2718CB metallocene linear low-density polyethylene, 0.04 parts by weight of 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, 0.1 parts by weight of barium sulfate, 0.01 parts by weight of oleamide, 2 parts by weight of polyol fatty acid ester, and 0.1 parts by weight of chlorinated paraffin are placed in a mixer and mixed for 20 minutes at room temperature with a speed of 200 rpm. Then, the mixed material is granulated in a twin-screw extruder with a blending temperature of 170℃, a die temperature of 160℃, and a screw extrusion speed of 100 rpm. After granulation, the material is dried in an oven at 50℃ to obtain a special material for medium-layer polyethylene cast film.

[0081] 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 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 8mm, and the bubble height is 3mm.

[0082] Preparation of bubble wrap:

[0083] After the bubble wrap has stabilized and formed, the prepared outer and inner polyethylene films are introduced into the machine via traction rollers to be laminated with the bubble wrap. The outer polyethylene film is laminated with the bubble wrap roller during the bubble wrap process, meaning that the outer polyethylene film is pressed together with the bubble wrap while the bubble is forming. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the inner polyethylene film. After edge trimming and winding, recyclable polyethylene bubble wrap is obtained.

[0084] 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 recyclable polyethylene bubble bag is obtained. The hot-pressing temperature is 91℃.

[0085] Tests showed that the tensile strength of the polyethylene bubble film described in the patent is 20.5 MPa, the elongation at break is 220.6%, and the melting points of each layer of special material are shown in Table 1.

[0086] Example 2

[0087] This embodiment provides a method for preparing recyclable polyethylene bubble bags, including:

[0088] Preparation of outer polyethylene film:

[0089] First, 100 parts by weight of high-density polyethylene, 4 parts by weight of 3518CB metallocene linear low-density polyethylene, 12 parts by weight of 9010 ethylene-octene block copolymer, 0.06 parts by weight of stilbene bisbenzoxazole, 2.5 parts by weight of fatty acid alkanolamide, and 0.5 parts by weight of antimony trioxide were placed in a mixer and mixed for 22 minutes at room temperature with a speed of 250 rpm. Then, the mixed material was granulated in a twin-screw extruder with a blending temperature of 187℃, a die temperature of 172℃, and a screw extrusion speed of 125 rpm. After granulation, the material was dried in an oven at 65℃ to obtain a special material for outer polyethylene film blow molding.

[0090] The outer polyethylene film blow molding material is fed into the blow molding machine, the processing temperature is set to 182℃, the blow-up ratio is 1.8, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a pull ratio of 3.4. Then it is cut and rolled up to obtain the outer polyethylene film.

[0091] Preparation of the inner polyethylene film:

[0092] First, 100 parts by weight of linear low-density polyethylene, 12 parts by weight of 3518CB metallocene linear low-density polyethylene, 15 parts by weight of 8411 ethylene-1-octene random copolymer, 0.17 parts by weight of hydrated magnesium silicate, 0.05 parts by weight of erucamide, 2.5 parts by weight of fatty acid alkanolamide, and 0.5 parts by weight of antimony trioxide were placed in a mixer and mixed for 22 minutes at room temperature with a speed of 250 rpm. Then, the mixed material was granulated in a twin-screw extruder with a blending temperature of 162℃, a die temperature of 152℃, 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 film blow molding.

[0093] The inner polyethylene film blowing material is fed into the blown film machine, the processing temperature is set to 162℃, the blow-up ratio is 2.2, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a pull ratio of 3.8. Then it is cut and rolled up to obtain the inner polyethylene film.

[0094] Preparation of the middle layer bubble film:

[0095] First, 100 parts by weight of low-density polyethylene, 15 parts by weight of 8411 ethylene-1-octene copolymer, 12 parts by weight of 3518CB metallocene linear low-density polyethylene, 0.06 parts by weight of stilbene bisbenzoxazole, 0.17 parts by weight of silica, 0.05 parts by weight of erucamide, 2.5 parts by weight of fatty acid alkanolamide, and 0.5 parts by weight of antimony trioxide were placed in a mixer and mixed for 22 minutes at room temperature at a speed of 250 rpm. Then, the mixed material was granulated in a twin-screw extruder at a blending temperature of 172℃, a die temperature of 165℃, 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 medium-layer polyethylene cast film.

[0096] The obtained medium-layer polyethylene cast film material is fed into a bubble film machine. The processing temperature is 192℃ 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 9mm, and the bubble height is 4mm.

[0097] Preparation of bubble wrap:

[0098] After the bubble wrap has stabilized and formed, the prepared outer and inner polyethylene films are introduced into the machine via traction rollers to be laminated with the bubble wrap. The outer polyethylene film is laminated with the bubble wrap roller during the bubble wrap process, meaning that the outer polyethylene film is pressed together with the bubble wrap while the bubble is forming. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the inner polyethylene film. After edge trimming and winding, recyclable polyethylene bubble wrap is obtained.

[0099] 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 recyclable polyethylene bubble bag is obtained. The hot-pressing temperature is 92℃.

[0100] Tests showed that the tensile strength of the polyethylene bubble film described in the patent was 19.6 MPa, the elongation at break was 245.2%, and the melting points of each layer of special material were shown in Table 1.

[0101] Example 3

[0102] This embodiment provides a method for preparing recyclable polyethylene bubble bags, including:

[0103] Preparation of outer polyethylene film:

[0104] First, 100 parts by weight of high-density polyethylene, 3 parts by weight of 3518CB and 3 parts by weight of 3518GA metallocene linear low-density polyethylene, 7 parts by weight of 9077 and 8 parts by weight of 9007 ethylene-octene block copolymer, 0.07 parts by weight of 1,4-bis(benzoxazolyl-2-yl)naphthalene, 3 parts by weight of fatty amine ethoxy ether, and 1 part by weight of aluminum hydroxide were placed in a mixer and mixed for 25 minutes at room temperature with a speed of 300 rpm. Then, the mixed material was granulated in a twin-screw extruder with a blending temperature of 190℃, 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 outer polyethylene film blow molding.

[0105] The outer polyethylene film blowing material is fed into the blown film machine, the processing temperature is set to 185℃, the blow-up ratio is 2.1, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a pull ratio of 3.7. Then it is cut and rolled up to obtain the outer polyethylene film.

[0106] Preparation of the inner polyethylene film:

[0107] First, 100 parts by weight of linear low-density polyethylene, 7 parts by weight of 2718CB and 3518GA metallocene linear low-density polyethylene, 10 parts by weight of 8411 and 10 parts by weight of 8452 ethylene-1-octene random copolymer, 0.12 parts by weight of diatomaceous earth, 0.13 parts by weight of molecular sieve, 0.05 parts by weight of erucamide and 0.05 parts by weight of stearamide, 3 parts by weight of fatty amine ethoxy ether, and 1 part by weight of aluminum hydroxide were placed in a mixer and mixed for 25 minutes at room temperature at a speed of 300 rpm. Then, the mixed material was granulated in a twin-screw extruder at a blending temperature of 165℃, a die temperature of 155℃, 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 film blow molding.

[0108] The inner polyethylene film blowing material is fed into the blown film machine, the processing temperature is set to 165℃, the blow-up ratio is 2.5, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a traction ratio of 4.0. Then it is cut and rolled up to obtain the inner polyethylene film.

[0109] Preparation of the middle layer bubble film:

[0110] First, 100 parts by weight of low-density polyethylene, 10 parts by weight of 8411 and 10 parts by weight of 8452 ethylene-1-octene copolymer, 7 parts by weight of 3518CB and 8 parts by weight of 3518GA metallocene linear low-density polyethylene, 0.07 parts by weight of 1,4-bis(benzoxazolyl-2-yl)naphthalene, 0.12 parts by weight of diatomaceous earth, 0.13 parts by weight of calcium sulfate, 0.05 parts by weight of erucamide and 0.05 parts by weight of stearamide, 3 parts by weight of fatty amine ethoxy ether, and 1 part by weight of aluminum hydroxide were placed in a mixer and mixed for 25 minutes at room temperature at a speed of 300 rpm. Then, the mixed material was granulated in a twin-screw extruder at a blending temperature of 175°C, a die temperature of 165°C, and a screw extrusion speed of 150 rpm. After granulation, the material was dried in an oven at 55°C to obtain a special material for medium-layer polyethylene cast film.

[0111] 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 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 10mm, and the bubble height is 5mm.

[0112] Preparation of bubble wrap:

[0113] After the bubble wrap has stabilized and formed, the prepared outer and inner polyethylene films are introduced into the machine via traction rollers to be laminated with the bubble wrap. The outer polyethylene film is laminated with the bubble wrap roller during the bubble wrap process, meaning that the outer polyethylene film is pressed together with the bubble wrap while the bubble is forming. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the inner polyethylene film. After edge trimming and winding, recyclable polyethylene bubble wrap is obtained.

[0114] Finally, the rolled polyethylene bubble film is introduced into the bag making machine, and after steps such as cutting, bending, and hot sealing, a recyclable polyethylene bubble bag is obtained. The hot sealing temperature is 93℃.

[0115] Tests showed that the tensile strength of the polyethylene bubble film described in the patent was 17.9 MPa, the elongation at break was 282.5%, and the melting points of each layer of special material were shown in Table 1.

[0116] Example 4

[0117] This embodiment provides a method for preparing recyclable polyethylene bubble bags, including:

[0118] Preparation of outer polyethylene film:

[0119] First, 100 parts by weight of high-density polyethylene, 4 parts by weight of 3518GA and 4 parts by weight of 4518PA metallocene linear low-density polyethylene, 9 parts by weight of 9077 and 9 parts by weight of 9100 ethylene-octene block copolymer, 0.04 parts by weight of 1,4-bis(benzoxazolyl-2-yl)naphthalene and 0.04 parts by weight of 4,4-bis(5-methyl-2-benzoxazolyl)stilbene, 1.7 parts by weight of fatty amine ethoxy ether and 1.8 parts by weight of phosphate fatty alcohol ester, 0.7 parts by weight of aluminum hydroxide and 0.8 parts by weight of magnesium hydroxide were placed in a mixer and mixed for 27 minutes at room temperature at a speed of 350 rpm. Then, the mixed material was granulated in a twin-screw extruder at a blending temperature of 192℃, 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 outer polyethylene film blow molding.

[0120] The outer polyethylene film blow molding material is fed into the blow molding machine, the processing temperature is set to 187℃, the blow-up ratio is 2.5, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a pull ratio of 4.1. Then it is cut and rolled up to obtain the outer polyethylene film.

[0121] Preparation of the inner polyethylene film:

[0122] First, 100 parts by weight of linear low-density polyethylene, 8 parts by weight of 3518CB and 9 parts by weight of 3518GA metallocene linear low-density polyethylene, 12 parts by weight of 8452 ethylene-1-octene random copolymer and 13 parts by weight of 7256 ethylene-1-butene random copolymer, 0.17 parts by weight of diatomaceous earth and 0.17 parts by weight of calcium carbonate, 0.07 parts by weight of oleamide and 0.08 parts by weight of behenamide, 1.7 parts by weight of fatty amine ethoxy ether and 1.8 parts by weight of phosphate fatty alcohol ester, 0.7 parts by weight of aluminum hydroxide and 0.8 parts by weight of magnesium hydroxide were placed in a mixer and mixed for 27 minutes at room temperature with a speed of 350 rpm. Then, the mixed material was granulated in a twin-screw extruder with a blending temperature of 167°C, a die temperature of 157°C and a screw extrusion speed of 175 rpm. After granulation, the material is dried in an oven at 57°C to obtain a special material for blow molding of inner polyethylene film.

[0123] The inner polyethylene film blowing material is fed into the blown film machine, the processing temperature is set to 167℃, the blow-up ratio is 2.7, the film is cooled by the air ring after molding, and then rotated and pulled with a pull ratio of 4.2. Then it is cut and wound up to obtain the inner polyethylene film.

[0124] Preparation of the middle layer bubble film:

[0125] First, 100 parts by weight of low-density polyethylene, 12 parts by weight of 8452 ethylene-1-octene copolymer, 13 parts by weight of 7256 ethylene-1-butene copolymer, 8 parts by weight of 2718CB and 9 parts by weight of 4518PA metallocene linear low-density polyethylene, 0.04 parts by weight of 1,4-bis(benzoxazolyl-2-yl)naphthalene and 0.04 parts by weight of 4,4-bis(5-methyl-2-benzoxazolyl)stilbene, 0.17 parts by weight of diatomaceous earth and 0.17 parts by weight of... Calcium phosphate, 0.07 parts by weight of oleamide and 0.08 parts by weight of behenamide, 1.7 parts by weight of fatty amine ethoxy ether and 1.8 parts by weight of fatty alcohol phosphate, 0.7 parts by weight of aluminum hydroxide and 0.8 parts by weight of magnesium hydroxide were placed in a mixer and mixed for 27 minutes at room temperature with a speed of 350 rpm. The mixture was then granulated in a twin-screw extruder with a blending temperature of 177°C, a die temperature of 167°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.

[0126] The obtained medium-layer polyethylene cast film material is fed into a bubble film machine. The processing temperature is 197℃ and the speed is set to 450 rpm. The extruded polyethylene is cast, vacuum adsorbed by the bubble roller, and compounded 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.

[0127] Preparation of bubble wrap:

[0128] After the bubble wrap has stabilized and formed, the prepared outer and inner polyethylene films are introduced into the machine via traction rollers to be laminated with the bubble wrap. The outer polyethylene film is laminated with the bubble wrap roller during the bubble wrap process, meaning that the outer polyethylene film is pressed together with the bubble wrap while the bubble is forming. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the inner polyethylene film. After edge trimming and winding, recyclable polyethylene bubble wrap is obtained.

[0129] 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 recyclable polyethylene bubble bag is obtained. The hot-pressing temperature is 94℃.

[0130] Tests showed that the tensile strength of the polyethylene bubble film described in the patent was 16.5 MPa, the elongation at break was 305.9%, and the melting points of each layer of special material were shown in Table 1.

[0131] Example 5

[0132] This embodiment provides a method for preparing recyclable polyethylene bubble bags, including:

[0133] Preparation of outer polyethylene film:

[0134] First, 100 parts by weight of high-density polyethylene, 3 parts by weight of 2718C, 3 parts by weight of 3518CB and 3 parts by weight of 4818PA metallocene linear low-density polyethylene, 5 parts by weight of 9077, 5 parts by weight of 9100 and 10 parts by weight of 9107 ethylene-octene block copolymer, 0.05 parts by weight of 4,4-bis(5-methyl-2-benzoxazolyl)stilbene and 0.05 parts by weight of 1,4-bis(5-methyl-2-benzoxazolyl)naphthalene, 2 parts by weight of polyol fatty acid ester and 2 parts by weight of phosphate fatty alcohol ester, 1 part by weight of chlorinated paraffin and 1 part by weight of magnesium hydroxide were placed in a mixer and mixed at room temperature for 30 minutes at a speed of 400 rpm. Then, the mixed material was granulated in a twin-screw extruder with a blending temperature of 195℃, a die temperature of 180℃ and a screw extrusion speed of 200 rpm. After granulation, the material is dried in an oven at 80°C to obtain a special material for blow molding of the outer polyethylene film.

[0135] The outer polyethylene film blow molding material is fed into the blow molding machine, the processing temperature is set to 190℃, the blow-up ratio is 2.8, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a pull ratio of 4.5. Then it is cut and rolled up to obtain the outer polyethylene film.

[0136] Preparation of the inner polyethylene film:

[0137] First, 100 parts by weight of linear low-density polyethylene, 7 parts by weight of 2718CB, 7 parts by weight of 3518CB and 6 parts by weight of 4518PA metallocene linear low-density polyethylene, 10 parts by weight of 8411 ethylene-1-octene random copolymer, 10 parts by weight of DF8200 and 10 parts by weight of A4085s ethylene-1-butene random copolymer, 0.2 parts by weight of talc and 0.2 parts by weight of calcium carbonate, 0.1 parts by weight of erucamide and 0.1 parts by weight of isostearamide, 2 parts by weight of polyol fatty acid ester and 2 parts by weight of phosphate fatty alcohol ester, 1 part by weight of chlorinated paraffin and 1 part by weight of magnesium hydroxide were placed in a mixer and mixed at room temperature for 30 minutes at a speed of 400 rpm. Then, the mixed material was granulated in a twin-screw extruder with a blending temperature of 170℃, a die temperature of 160℃ and a screw extrusion speed of 200 rpm. After granulation, the material is dried in an oven at 60°C to obtain a special material for blow molding of inner polyethylene film.

[0138] The inner polyethylene film blowing material is fed into the blown film machine, the processing temperature is set to 170℃, the blow-up ratio is 3.0, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a pull ratio of 4.5. Then it is cut and rolled up to obtain the inner polyethylene film.

[0139] Preparation of the middle layer bubble film:

[0140] First, 100 parts by weight of low-density polyethylene, 10 parts by weight of 8452 ethylene-1-octene copolymer, 10 parts by weight of DF8200 and 10 parts by weight of A4085s ethylene-1-butene copolymer, 7 parts by weight of 3518CB, 7 parts by weight of 3518GA and 6 parts by weight of 4518PA metallocene linear low-density polyethylene, 0.05 parts by weight of 4,4-bis(5-methyl-2-benzoxazolyl)stilbene and 0.05 parts by weight of 1,4-bis(5-methyl-2-benzoxazolyl)naphthalene, 0.2 parts by weight of silica and 0.2 parts by weight of calcium sulfate, 0.1 parts by weight of erucamide and 0.1 parts by weight of isostearamide, 2 parts by weight of polyol fatty acid ester and 2 parts by weight of phosphate fatty alcohol ester, 1 part by weight of chlorinated paraffin and 1 part by weight of magnesium hydroxide were placed in a mixer and mixed at room temperature for 30 minutes at a speed of 400 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 200 rpm. After granulation, the mixture was dried in an oven at 60°C to obtain a special material for medium-layer polyethylene cast film.

[0141] 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 500 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.

[0142] Preparation of bubble wrap:

[0143] After the bubble wrap has stabilized and formed, the prepared outer and inner polyethylene films are introduced into the machine via traction rollers to be laminated with the bubble wrap. The outer polyethylene film is laminated with the bubble wrap roller during the bubble wrap process, meaning that the outer polyethylene film is pressed together with the bubble wrap while the bubble is forming. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the inner polyethylene film. After edge trimming and winding, recyclable polyethylene bubble wrap is obtained.

[0144] 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 recyclable polyethylene bubble bag is obtained. The hot-pressing temperature is 95℃.

[0145] Tests showed that the tensile strength of the polyethylene bubble film described in the patent was 17.1 MPa, the elongation at break was 336.5%, and the melting points of each layer of special material were shown in Table 1.

[0146] Comparative Example 1

[0147] Preparation of outer polyethylene film:

[0148] First, 100 parts by weight of high-density polyethylene, 0.04 parts by weight of 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, 2 parts by weight of polyol fatty acid ester antistatic agent, and 0.1 parts by weight of chlorinated paraffin are placed in a mixer and mixed for 20 minutes at room temperature with a speed of 200 rpm. Then, the mixed material is granulated in a twin-screw extruder with a blending temperature of 185℃, a die temperature of 170℃, and a screw extrusion speed of 100 rpm. After granulation, the material is dried in an oven at 60℃ to obtain a special material for outer polyethylene film blow molding.

[0149] The outer polyethylene film blowing material is fed into the blown film machine, the processing temperature is set to 180℃, the blow-up ratio is 1.5, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a traction ratio of 3.0. Then it is cut and rolled up to obtain the outer polyethylene film.

[0150] Preparation of the inner polyethylene film:

[0151] First, 100 parts by weight of linear low-density polyethylene, 0.1 parts by weight of talc, 0.01 parts by weight of oleamide, 2 parts by weight of polyol fatty acid ester antistatic agent, and 0.1 parts by weight of chlorinated paraffin are placed in a mixer and mixed for 20 minutes at room temperature with a speed of 200 rpm. Then, the mixed material is granulated in a twin-screw extruder with a blending temperature of 160℃, a die temperature of 150℃, and a screw extrusion speed of 100 rpm. After granulation, the material is dried in an oven at 50℃ to obtain a special material for inner layer polyethylene film blow molding.

[0152] The inner polyethylene film blowing material is fed into the blown film machine, the processing temperature is set to 160℃, the blow-up ratio is 2.0, after molding, the air ring is cooled, and after cooling, it is rotated and pulled with a pull ratio of 3.5. Then it is cut and rolled up to obtain the inner polyethylene film.

[0153] Preparation of the middle layer bubble film:

[0154] First, 100 parts by weight of low-density polyethylene, 0.04 parts by weight of 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, 0.1 parts by weight of barium sulfate, 0.01 parts by weight of oleamide, 2 parts by weight of polyol fatty acid ester, and 0.1 parts by weight of chlorinated paraffin are placed in a mixer and mixed for 20 minutes at room temperature with a speed of 200 rpm. Then, the mixed material is granulated in a twin-screw extruder with a blending temperature of 170℃, a die temperature of 160℃, and a screw extrusion speed of 100 rpm. After granulation, the material is dried in an oven at 50℃ to obtain a special material for medium-layer polyethylene cast film.

[0155] 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 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 8mm, and the bubble height is 3mm.

[0156] Preparation of bubble wrap:

[0157] After the bubble wrap has stabilized and formed, the prepared outer and inner polyethylene films are introduced into the machine via traction rollers to be laminated with the bubble wrap. The outer polyethylene film is laminated with the bubble wrap roller during the bubble wrap process, meaning that the outer polyethylene film is pressed together with the bubble wrap while the bubble is forming. Immediately afterwards, the side of the bubble wrap with the bubbles is pressed together with the inner polyethylene film. After edge trimming and winding, recyclable polyethylene bubble wrap is obtained.

[0158] 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 recyclable polyethylene bubble bag is obtained. The hot-pressing temperature is 91℃.

[0159] Tests showed that the tensile strength of the polyethylene bubble film described in the patent was 20.1 MPa, the elongation at break was 189.3%, and the melting points of each layer of special material were shown in Table 1.

[0160] Table 1 Melting points of each layer of polyethylene bubble film

[0161] Example 1 131.4 109.8 116.5 Example 2 130.1 108.6 115.0 Example 3 128.9 107.2 113.2 Example 4 127.6 105.1 110.9 Example 5 125.8 103.2 109.1 Comparative Example 133.9 113.5 121.7

[0162] 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 recyclable polyethylene bubble bag, characterized in that, The polyethylene bubble bag comprises, in sequence, an outer layer of polyethylene blown film, a middle layer of polyethylene cast bubble film, and an inner layer of polyethylene blown film. The raw materials of the outer layer of polyethylene blown film, by weight, include: 100 parts of high-density polyethylene, 2-10 parts of metallocene linear low-density polyethylene, 10-20 parts of a first toughening agent, 0.04-0.1 parts of a whitening agent, 2-4 parts of an antistatic agent, and 0.1-2 parts of a flame retardant. The raw materials of the middle layer polyethylene cast bubble film, by weight, include: 100 parts of low-density polyethylene, 10-30 parts of a second toughening agent, 10-20 parts of metallocene linear low-density polyethylene, 0.04-0.1 parts of a whitening agent, 0.1-0.4 parts of a first opening agent, 0.01-0.2 parts of a slip agent, 2-4 parts of an antistatic agent, and 0.1-2 parts of a flame retardant; The raw materials of the inner polyethylene blown film, by weight, include: 100 parts of linear low-density polyethylene, 10-20 parts of metallocene linear low-density polyethylene, 10-30 parts of a second toughening agent, 0.1-0.4 parts of a second opening agent, 0.01-0.2 parts of a slip agent, 2-4 parts of an antistatic agent, and 0.1-2 parts of a flame retardant; In the raw material of the outer polyethylene blown film, the density of the high-density polyethylene is 0.941-0.965 g / cm³. 3 The melt flow index is 2.0-3.0 g / 10 min, and the first toughening agent is an ethylene-α-olefin block copolymer; In the raw materials of the middle-layer polyethylene cast bubble film, the density of the low-density polyethylene is 0.910-0.925 g / cm³. 3 The first toughening agent has a melt index of 4.0-5.0 g / 10 min; the second toughening agent is an ethylene-α-olefin random copolymer, which is a low-temperature elastomer obtained by random copolymerization of ethylene with 1-butene or 1-octene, with a melt index of 2.0-20.0 g / 10 min and a melting point of 55-80℃. In the raw materials for the inner layer polyethylene blown film, the linear low-density polyethylene has a density of 0.910-0.925 g / cm³. 3 The melt flow index is 2.0-3.0 g / 10 min; the metallocene linear low-density polyethylene is a linear low-density polyethylene obtained by metallocene-catalyzed copolymerization of ethylene and higher olefins, with a melt flow index of 2-5 g / min and a density of 0.910-0.927 g / cm³. 3 .

2. The recyclable polyethylene bubble bag according to claim 1, characterized in that, The metallocene linear low-density polyethylene is one or more of 2718CB, 3518CB, 3518GA, and 4518PA metallocene linear low-density polyethylene.

3. The recyclable polyethylene bubble bag according to claim 1, characterized in that, The whitening agent is one or more of 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, stilbene bisbenzoxazole, 1,4-bis(benzoxazolyl-2-yl)naphthalene, 4,4-bis(5-methyl-2-benzoxazolyl)stilbene, and 1,4-bis(5-methyl-2-benzoxazolyl)naphthalene; The antistatic agent is one or more of the following: polyol fatty acid esters, fatty acid alkanolamides, fatty amine ethoxy ethers, and phosphate fatty alcohol esters. The flame retardant is one or more of chlorinated paraffin, antimony trioxide, aluminum hydroxide, and magnesium hydroxide; The first opening agent of the middle layer polyethylene cast film is one or more of barium sulfate, silicon dioxide, calcium sulfate, dicalcium phosphate and diatomaceous earth, and the particle size of the opening agent is 50-200nm. The second opening agent of the inner polyethylene blown film is one or more of talc, hydrated magnesium silicate, diatomaceous earth, molecular sieve and calcium carbonate, and the particle size of the opening agent is 50-200nm. The slip agent is one or more of the following: erucamide, behenamide, stearamide, and isostearamide migratory primary amide slip agents.

4. A method for preparing a recyclable polyethylene bubble bag as described in any one of claims 1-3, characterized in that, The preparation method includes the following steps: 1) Preparation of outer polyethylene film: According to the formula, high-density polyethylene, metallocene linear low-density polyethylene, first toughening agent, whitening agent, antistatic agent and flame retardant are placed in a mixer, and the mixed material is granulated in a twin-screw extruder; after granulation, it is dried to obtain the outer polyethylene film blow molding material; the outer polyethylene film blow molding material is fed into a blown film machine, formed and cooled by an air ring, and after cooling, it is rotated and pulled, cut and wound to obtain the outer polyethylene film; 2) Preparation of inner polyethylene film: According to the formula, linear low-density polyethylene, metallocene linear low-density polyethylene, second toughening agent, second opening agent, slip agent, antistatic agent and flame retardant are placed in a mixer, and the mixed material is granulated in a twin-screw extruder; after granulation, it is dried to obtain inner polyethylene film blow molding material; the inner polyethylene film blow molding material is fed into a blown film machine, formed and cooled by an air ring, and after cooling, it is rotated and pulled, cut and wound to obtain inner polyethylene film; 3) Preparation of middle layer bubble film: According to the formula, low-density polyethylene, second toughening agent, metallocene linear low-density polyethylene, whitening agent, first opening agent, slip agent, antistatic agent and flame retardant are placed in a mixer, and the mixed material is granulated in a twin-screw extruder; after granulation, it is dried to obtain a middle layer polyethylene cast film blow molding material; the obtained middle layer polyethylene cast film blow molding material is fed into a bubble film machine, and the extruded polyethylene is cast, vacuum adsorbed by bubble rollers, and compounded into bubble film; 4) After the bubble film obtained in step 3) has stabilized and formed, the outer polyethylene film prepared in step 1) and the inner polyethylene film prepared in step 2) are introduced into the machine through the traction roller to be laminated with the bubble film; the outer polyethylene 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 polyethylene film. Then, the side of the bubble film that forms the bubble is pressed together with the inner polyethylene film. After cutting the edges and winding, a recyclable polyethylene bubble film is obtained. Finally, the rolled polyethylene bubble film is introduced into the bag making machine, and after cutting, bending and hot-pressing the edges, a recyclable polyethylene bubble bag is obtained. The hot-pressing temperature is 90-95℃.

5. The method for preparing a recyclable polyethylene bubble bag according to claim 4, characterized in that, In step 1), the mixer conditions are: mixing at room temperature for 20-30 minutes at a speed of 200-400 rpm; the twin-screw extrusion conditions are: blending temperature 185-195℃, die temperature 170-180℃, screw extrusion speed 100-200 rpm, and drying temperature after granulation 60-80℃; the blown film processing temperature is 180-190℃, and the blow-up ratio is 1.5-2.8; the rotary traction process has a traction ratio of 3.0-4.

5. In step 2), the mixing conditions are as follows: mixing at room temperature for 20-30 minutes and a speed of 200-400 rpm; the twin-screw extrusion conditions are: blending temperature 160-170℃, die temperature 150-160℃, screw extrusion speed 100-200 rpm, and drying temperature after granulation 50-60℃; the processing temperature during blown film extrusion is 160-170℃ and the blow-up ratio is 2.0-3.0; and the traction ratio during rotary traction is 3.5-4.

5.

6. The method for preparing a recyclable polyethylene bubble bag according to claim 4, characterized in that, In step 3), the mixing conditions are as follows: mixing at room temperature for 20-30 minutes and a rotation speed of 200-400 rpm; the twin-screw extrusion conditions are: blending temperature of 170-180℃, die temperature of 160-170℃, screw extrusion speed of 100-200 rpm, and drying temperature after granulation of 50-60℃; the processing temperature in the bubble film machine is 190-200℃ and the rotation speed is 300-500 rpm; the vacuum degree of the bubble roller is 0.04MPa, the bubble diameter is 8-12mm, and the bubble height is 3-7mm.

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