A recyclable high-strength antibacterial polyethylene bubble film and its preparation method

Abstract

The present invention discloses a recyclable high-strength antibacterial polyethylene bubble film and a preparation method thereof. The present invention uses ethylene-acrylic acid random copolymer as a compatibilizer, and is synergistically modified with inorganic fillers to prepare a high-strength high-density polyethylene outer protective film. The low-density polyethylene bubble film is synergistically modified by using metallocene low-density polyethylene and ethylene-α-olefin elastomer. All polyethylene-based materials are used, and the organic combination of different molecular chain structures is utilized to improve the comprehensive mechanical properties of the bubble film and facilitate recycling and reuse. The bubble film is functionally modified with a bio-based extract as an antibacterial agent and an antioxidant, and the antibacterial effect is lasting and effective. All processing aids used are non-toxic and harmless materials. The recyclable high-strength antibacterial bubble film prepared can be widely used in fields such as medicine and food packaging.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, relates to bubble film, and particularly relates to a recyclable high-strength antibacterial polyethylene bubble film and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of the market economy, the waste volume of disposable cushioning packaging materials has been increasing year by year, causing serious harm to the environment. The waste problem caused by non-degradable plastics urgently needs to be solved. Since 2015, the global plastic waste production has continued to increase, exceeding 300 million tons per year. Facing the increasingly severe global plastic pollution crisis, it has become the general trend to create a plastic closed-loop through recycling and reuse, improve the recycling level of plastic resources, and shift from a linear economy to a sustainable green circular economy. The whole-chain governance of plastic pollution has been proposed, strengthening the classification, recycling and reuse of plastic waste, planning to vigorously develop a circular economy including plastic recycling, focusing on solving prominent contradictions and problems, realizing the efficient utilization and recycling of plastics, and promoting the high-quality development of the economic society. Therefore, it is imperative to develop recyclable polyethylene bubble bags.

[0003] Patent CN 112208178A uses polypropylene to increase the stiffness of the polyethylene film and prepares a three-layer co-extruded film compounded with the bubble film. This method uses a large amount of polypropylene and its copolymers, and the material after compounding with the bubble film is difficult to recycle and reuse.

[0004] Patent CN103435885A toughens low-density polyethylene resin with ethylene-vinyl acetate elastomer to obtain a highly tough degradable flame-retardant bubble film. However, while toughening with ethylene-vinyl acetate, the strength of the material will be lost, resulting in insufficient stiffness of the bubble film.

[0005] CN109294027A uses a commercially available water- and oil-resistant film as a protective film to prepare a degradable high-strength composite bubble film. This method increases the strength by using a composite high-strength outer film, cannot directly increase the stiffness of the bubble film, and does not consider the interfacial bonding strength, so the overall strengthening effect is not good. In addition, this patent uses silver ion antibacterial agent to improve the antibacterial property of the bubble film. Although silver ion antibacterial agent has a strong bactericidal effect, it is not easy to add too much silver ion antibacterial agent, otherwise it will cause harm to human health.

[0006] Traditional bubble wrap and bubble bags are mainly made of various materials such as polyethylene and polypropylene. Due to the high mismatch in physical and processing properties of different materials, it is impossible to use a unified recycling and processing technology to prepare recycled materials. Moreover, the difficulty of peeling between layers is large, resulting in the inability to recycle and reuse. After use, they are often directly discarded. Secondly, with the development of the packaging industry, the functional requirements for bubble wrap also tend to be diversified. In addition to the basic mechanical properties such as stiffness and toughness of bubble wrap, it is also required to have antibacterial, antioxidant, antistatic properties, etc. However, traditional processing aids often have some toxicity and can cause harm to the human body. For example, silver ion antibacterial agents, although they have excellent bactericidal properties, their content needs to be strictly controlled, and excessive amounts will cause harm to human health. Another example is dibutylhydroxytoluene and tert-butylhydroquinone. They have good antioxidant properties. However, further research shows that they have certain toxicity and cause certain harm to the human body, manifested in carcinogenesis, teratogenesis and mutagenesis.

[0007] Therefore, the research focus on polyethylene bubble wrap mainly focuses on improving mechanical properties and functional modification. On the premise of ensuring safety and non-toxicity, it should also be recyclable and reusable, and there is currently no product that organically unifies them. Therefore, it is very important to develop a recyclable high-strength polyethylene antibacterial bubble wrap. Summary of the Invention

[0008] To solve the above problems, the present invention provides a recyclable high-strength antibacterial polyethylene bubble wrap and its preparation method. The present invention uses ethylene-acrylic acid random copolymer as a compatibilizer and synergistically modifies it with inorganic fillers to prepare a high-strength high-density polyethylene outer protective film. The low-density polyethylene bubble wrap is synergistically modified by metallocene low-density polyethylene and ethylene-α-olefin elastomer. All polyethylene-based materials are used, and the comprehensive mechanical properties of the bubble wrap are improved by the organic combination of different molecular chain structures, and it is also convenient for recycling and reuse. The bubble wrap is functionally modified with bio-based extracts as antibacterial agents and antioxidants, and the antibacterial effect is lasting and effective. The processing aids used are all non-toxic and harmless materials. The recyclable high-strength antibacterial bubble wrap prepared can be widely used in fields such as medicine and food packaging.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] The present invention provides a recyclable high-strength antibacterial polyethylene bubble film, which includes an outer protective film and an inner polyethylene bubble film. The raw materials of the outer protective film include, by weight, 100 parts of high-density polyethylene (HDPE), 2-4 parts of a compatibilizer, 2-4 parts of an inorganic filler, 2-10 parts of metallocene linear low-density polyethylene (mLLDPE), 1-3 parts of a plasticizer, 3-5 parts of an antibacterial agent, 2-4 parts of an antioxidant, and 1-3 parts of an antistatic agent.

[0011] The raw materials of the inner layer polyethylene bubble film include: 100 parts of low-density polyethylene (LDPE), 10-20 parts of low-density linear polyethylene (LLDPE), 10-30 parts of ethylene-α-olefin elastomer, 10-20 parts of metallocene linear low-density polyethylene (mLLDPE), 3-5 parts of antibacterial agent, 2-4 parts of antioxidant, 1-3 parts of antistatic agent, 0.1-0.4 parts of anti-blocking agent, 0.01-0.2 parts of lubricating agent and 2-4 parts of inorganic filler.

[0012] In the present invention, ethylene-acrylic acid random copolymer is used as a compatibilizer and modified in coordination with an inorganic filler to prepare a high-strength high-density polyethylene outer protective film, while increasing the strength and toughness of the high-density polyethylene.

[0013] The low-density polyethylene bubble film is modified synergistically with metallocene low-density polyethylene and ethylene-α-olefin elastomer, and the organic combination of different molecular structures is used to make the molecular segments entangled with each other and improve the interlayer compatibility.

[0014] All polyethylene-based materials are used to improve the comprehensive mechanical properties of the bubble film while the product can be recycled and reused.

[0015] The bubble film is functionally modified using bio-based extracts as antibacterial agents and antioxidants, and the antibacterial effect is long-lasting and effective. The processing aids used are all non-toxic and harmless materials.

[0016] As a preferred embodiment of the present invention, the density of the high-density polyethylene in the raw material of the outer protective film is 0.941-0.965 g / cm 3 , the melt index is 2.0-3.0g / 10min; the compatibilizer is an ethylene-acrylic acid random copolymer with an acrylic acid content of 6-10% and a melt index of 3-5g / 10min.

[0017] As a preferred embodiment of the present invention, the density of the low-density polyethylene in the raw material of the inner polyethylene bubble film is 0.910-0.925 g / cm 3, the melt index is 4.0 - 5.0 g / 10 min; the density of the low-density linear polyethylene is 0.910 - 0.925 g / cm 3 , the melt index is 4.0 - 5.0 g / 10 min; the ethylene-α-olefin elastomer is an elastomer (POE) obtained by the random copolymerization of ethylene with 1-butene or 1-octene, and the melt index is 2.0 - 20.0 g / 10 min.

[0018] As a preferred embodiment of the present invention, the ethylene-α-olefin elastomer is one or more of the ethylene-1-octene random copolymers 8200, 8401, 8402, 8411 and 8452, and the ethylene-1-butene random copolymers 7256, DF740, DF8200, DF140 and A4085s.

[0019] In the present invention, the ethylene-α-olefin elastomer used does not limit other grades of POE.

[0020] As a preferred embodiment of the present invention, the metallocene linear low-density polyethylene is a linear low-density polyethylene obtained by the copolymerization of ethylene with a small amount of higher olefins catalyzed by metallocene, the melt index is 2 - 5 g / 10 min, and the density is 0.910 - 0.927 g / cm 3 .

[0021] As a preferred embodiment of the present invention, the metallocene linear low-density polyethylene is 2718CB,

[0022] one or more of the metallocene linear low-density polyethylenes 3518CB, 3518GA, and 4518PA.

[0023] In the present invention, the metallocene linear low-density polyethylene used does not limit other grades of mLLDPE.

[0024] As a preferred embodiment of the present invention, the bacteriostatic agent is one or more of cinnamaldehyde, citral, eugenol, isoeugenol, thymol, apple peel polyphenols, allicin, and vanillin;

[0025] The antioxidant is one or more of tea polyphenols, quercetin, grape tannin, curcumin, tocopherol, and resveratrol;

[0026] The antistatic agent is one or more of ethoxylated laurylamide, ethoxylated fatty amine, glycerol monostearate, glycerol monopalmitate, and glycerol polyethylene glycol ester;

[0027] The inorganic filler is one or more of hydrotalcite, illite, mica, montmorillonite, and kaolin, and the average particle size is 200 - 400 nm;

[0028] The plasticizer is one or more of citrate ester, tributyl citrate, tributyl acetyl citrate, and glyceryl triacetate;

[0029] The antiblocking agent is one or more of talcum powder, silica, calcium sulfate, calcium hydrogen phosphate, and diatomaceous earth, and the particle size of the antiblocking agent is 50 - 200 nm;

[0030] The slip agent is one or more of oleic acid amide, erucic acid amide, behenic acid amide, stearic acid amide, and isostearic acid amide.

[0031] The present invention also provides a method for preparing the above - mentioned recyclable high - strength antibacterial polyethylene bubble film, and the preparation method includes the following steps:

[0032] 1) Preparation of the outer protective film:

[0033] Put high - density polyethylene, compatibilizer, inorganic filler, metallocene linear low - density polyethylene, plasticizer, antibacterial agent, antioxidant, and antistatic agent in accordance with the formula amount into a mixer, and granulate the mixed materials in a twin - screw extruder; after granulation, dry to obtain the special material for the outer protective film;

[0034] Put the special material for the outer protective film into a blown - film machine, cool it with an air ring after forming, perform rotary traction after cooling, cut and wind it up to obtain the outer protective film;

[0035] 2) Preparation of the bubble film:

[0036] Put low - density polyethylene, low - density linear polyethylene, ethylene - α - olefin elastomer, metallocene linear low - density polyethylene, antibacterial agent, antioxidant, antistatic agent, antiblocking agent, slip agent, and inorganic filler in accordance with the formula amount into a mixer, and granulate the mixed materials in a twin - screw extruder; after granulation, dry to obtain the special material for the inner - layer bubble film;

[0037] 3) Put the obtained special material for the inner - layer bubble film into a bubble - film machine, extrude the polyethylene through casting, vacuum adsorption by a bubble roller, and prepare it into a bubble film; after the bubble film is stably formed, introduce the prepared outer protective film into the machine through a traction roller and compound it with the bubble film; the outer protective film is compounded with the inner - layer bubble film at the bubble roller, that is, while forming the bubble film, it is pressed together with the outer protective film; finally, after trimming and winding, a recyclable high - strength polyethylene antibacterial bubble film is obtained.

[0038] As a preferred embodiment of the present invention, in step 1), the conditions for stirring are mixing at room temperature for 20 - 30 min with a rotation speed of 200 - 400 revolutions per minute; during granulation, the blending temperature is 185 - 195 °C, the die temperature is 170 - 180 °C, and the screw extrusion rotation speed is 100 - 200 revolutions per minute; the drying temperature after granulation is 60 - 80 °C; the processing temperature of the blown film machine is 185 - 195 °C, and the blow-up ratio is 1.5 - 2.8; the draw ratio during rotary traction is 3.0 - 4.5.

[0039] As a preferred embodiment of the present invention, in step 2), the conditions for stirring are mixing at room temperature for 20 - 30 min with the rotation speed set at 200 - 400 revolutions per minute; during granulation, the blending temperature is 170 - 180 °C, the die temperature is 160 - 170 °C, and the screw extrusion rotation speed is 100 - 200 revolutions per minute; the drying temperature after granulation is 50 - 60 °C;

[0040] The processing temperature of the bubble film machine is 190 - 200 °C, the rotation speed is set at 300 - 500 revolutions per minute; the vacuum degree of the bubble roller is 0.04 MPa, the bubble hole diameter is 8 - 12 mm, and the bubble height is 3 - 7 mm.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1) By using the method of the present invention to prepare a recyclable high-strength antibacterial polyethylene bubble film, the comprehensive mechanical properties of the bubble film are improved, and it has good antibacterial, antistatic and other properties, which are safe, non-toxic and harmless, and can be applied to packaging fields such as medicine and food.

[0043] 2) In the recyclable polyethylene bubble film obtained by the preparation method described in the present invention, the molecules are intertangled with each other, and the comprehensive mechanical properties are excellent. It can be recycled and reused, and has a long-lasting and efficient antibacterial and antioxidant ability, and the product has high application value.

[0044] 3) Compared with the existing methods, the method of the present invention uses all polyethylene-based materials to replace traditional materials such as polypropylene, and utilizes the entanglement effect of the molecular structures of ethylene-α-olefin elastomer, metallocene low-density polyethylene and low-density polyethylene to improve the comprehensive mechanical properties. And a bio-based extract is used as an antibacterial agent and an antioxidant to functionalize and modify the bubble film, which is safe, efficient, non-toxic and harmless.

[0045] 4) The preparation method of the recyclable high-strength antibacterial polyethylene bubble film described in the present invention is simple and efficient, and all uses polyethylene-based materials, which solves the "plastic pollution" problem brought by traditional bubble bags, and provides a feasible solution for the development of plastic recycling processing-related industries. Specific embodiments

[0046] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0047] In the present invention, the raw materials, reagents or equipment used can be purchased from the market.

[0048] The preparation method of the recyclable high-strength antibacterial polyethylene bubble film provided by the present invention includes the following technical solutions:

[0049] Preparation of the outer protective film:

[0050] First, 100 parts by weight of high-density polyethylene, 2-4 parts by weight of compatibilizer, 2-4 parts by weight of inorganic filler, 2-10 parts by weight of metallocene linear low-density polyethylene, 1-3 parts by weight of plasticizer, 3-5 parts by weight of antibacterial agent, 2-4 parts by weight of antioxidant, and 1-3 parts by weight of antistatic agent are placed in a mixer and mixed at room temperature for 20-30 min with a rotation speed set at 200-400 rpm. Then, the mixed material is granulated in a twin-screw extruder with the blending temperature set at 185-195 °C, the die head temperature set at 170-180 °C, and the screw extrusion rotation speed at 100-200 rpm. After granulation, it is dried in an oven at 60-80 °C to obtain the special material for the outer protective film.

[0051] The special material for the outer protective film is put into a blown film machine with the processing temperature set at 185-195 °C, the blow-up ratio at 1.5-2.8. After forming, it is cooled by an air ring, and after cooling, it is rotationally drawn with a draw ratio of 3.0-4.5. Then, it is cut and wound to obtain the outer protective film.

[0052] Preparation of the bubble film:

[0053] First, 100 parts by weight of low-density polyethylene, 10-20 parts by weight of low-density linear polyethylene, 10-30 parts by weight of ethylene-α-olefin elastomer, 10-20 parts by weight of metallocene linear low-density polyethylene, 3-5 parts by weight of bacteriostat, 2-4 parts by weight of antioxidant, 1-3 parts by weight of antistatic agent, 0.1-0.4 parts by weight of antiblocking agent, 0.01-0.2 parts by weight of slip agent, and 2-4 parts by weight of inorganic filler are placed in a blender and mixed at room temperature for 20-30 min with a rotation speed set at 200-400 rpm. Then, the mixed material is granulated in a twin-screw extruder with the blending temperature set at 170-180 °C, the die head temperature set at 160-170 °C, and the screw extrusion rotation speed at 100-200 rpm. After granulation, it is dried in an oven at 50-60 °C to obtain the special material for the inner layer of bubble film.

[0054] The obtained special material for the inner layer of bubble film is put into a bubble film machine. The processing temperature is 190-200 °C, and the rotation speed is set at 300-500 rpm. The extruded polyethylene is processed through casting, vacuum adsorption by a bubble roller, and a bubble film is prepared. The vacuum degree of the bubble roller is 0.04 MPa, the bubble hole diameter is 8-12 mm, and the bubble height is 3-7 mm. After the bubble film is stably formed, the prepared outer protective film is introduced into the machine through a traction roller and compounded with the bubble film. The outer protective film is compounded with the inner layer of bubble film at the bubble roller, that is, it is pressed together with the outer protective film while the bubble film is being formed. Finally, through trimming and winding, a recyclable high-strength polyethylene bacteriostatic bubble film is obtained.

[0055] Performance Evaluation

[0056] 1. Tensile Mechanical Properties

[0057] The special materials for the outer protective film and the inner layer of bubble film are respectively made into 1-mm sheets by a flat vulcanizing machine, and then cut into dumbbell shapes of 20 mm×4 mm×1 mm. They are tested with a universal tensile testing machine according to ASTM D63-2014 at a tensile speed of 50 mm / min. Five groups are measured in parallel, and the results are the average values of the five groups of data.

[0058] 2. Bacteriostatic Performance

[0059] According to "GB / T 31402-2015 Plastics - Test Method for Antibacterial Properties of Plastic Surfaces", the bacteriostatic performance of polyethylene bubble film against Escherichia coli and Staphylococcus aureus is tested. Five groups are tested in parallel, and the bacteriostatic rate results are the average values of the five groups of data.

[0060] 3. Antioxidation

[0061] The scavenging ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals in polyethylene bubble film was determined by spectrophotometry, using absolute ethanol as a reference. The calculation formula for the DPPH scavenging rate is as follows:

[0062] Scavenging rate = (X D - X) ÷ X D × 100%

[0063] Where X D is the absorbance value of the DPPH ethanol solution without sample at 517 nm, and X sample is the absorbance value of the sample at 517 nm. Five groups were measured in parallel, and the results were the average of the five groups of data.

[0064] Example

[0065] This example provides a method for preparing recyclable high-strength antibacterial polyethylene bubble film, including:

[0066] Preparation of the outer protective film:

[0067] First, 100 parts by weight of high-density polyethylene, 2 parts by weight of ethylene-acrylic acid random copolymer, 2 parts by weight of hydrotalcite, 2 parts by weight of metallocene linear low-density polyethylene, 1 part by weight of citrate, 3 parts by weight of cinnamaldehyde, 2 parts by weight of tea polyphenols, and 1 part by weight of ethoxylated laurylamide were placed in a blender and mixed at room temperature for 20 min with a rotation speed set at 200 rpm. Then, the mixed material was granulated in a twin-screw extruder with a blending temperature set at 185°C, a die head temperature set at 170°C, and a screw extrusion speed of 100 rpm. After granulation, it was dried in an oven at 60°C to obtain a special material for blow molding of the outer polyethylene film.

[0068] The special material for blow molding of the outer polyethylene film was put into a blown film machine with a processing temperature set at 185°C, a blow-up ratio of 1.5. After forming, it was cooled by an air ring, and after cooling, it was rotationally drawn with a draw ratio of 3.0. Then, it was cut and wound to obtain the outer protective film.

[0069] Preparation of the bubble film:

[0070] First, 100 parts by weight of low-density polyethylene, 10 parts by weight of low-density linear polyethylene, 10 parts by weight of 8200 ethylene-1-octene copolymer, 10 parts by weight of 2718CB metallocene linear low-density polyethylene, 3 parts by weight of cinnamaldehyde, 2 parts by weight of tea polyphenols, 1 part by weight of ethoxylated laurylamide, 0.1 part by weight of talc, 0.01 part by weight of oleamide, and 2 parts by weight of hydrotalcite are placed in a blender and mixed at room temperature for 20 min with a rotation speed set at 200 revolutions / min. Then, the mixed material is granulated in a twin-screw extruder with a blending temperature set at 170 °C, a die head temperature set at 160 °C, and a screw extrusion rotation speed of 100 revolutions / min. After granulation, it is dried in an oven at 50 °C to obtain the special material for the inner layer of bubble film.

[0071] The obtained special material for the inner layer of bubble film is put into a bubble film machine with a processing temperature of 190 °C and a rotation speed set at 300 revolutions / min. The extruded polyethylene is processed through casting, vacuum adsorption by a bubble roller, and prepared into a bubble film with a vacuum degree of 0.04 MPa for the bubble roller, a bubble hole diameter of 8 mm, and a bubble height of 3 mm. After the bubble film is stably formed, the prepared outer protective film is introduced into the machine through a traction roller and compounded with the bubble film. The outer protective film is compounded with the inner layer of bubble film at the bubble roller, that is, it is pressed together with the outer protective film while the bubble film is being formed. Finally, through edge trimming and winding, a recyclable high-strength polyethylene antibacterial bubble film is obtained.

[0072] The test results are shown in Table 1.

[0073] Example

[0074] This example provides a method for preparing a recyclable high-strength antibacterial polyethylene bubble film, including:

[0075] Preparation of the outer protective film:

[0076] First, 100 parts by weight of high-density polyethylene, 2.5 parts by weight of ethylene-acrylic acid random copolymer, 2.5 parts by weight of illite, 4 parts by weight of metallocene linear low-density polyethylene, 1.5 parts by weight of tributyl citrate, 3.5 parts by weight of citral, 2.5 parts by weight of quercetin, and 1.5 parts by weight of ethoxylated fatty amine are placed in a blender and mixed at room temperature for 22 min with a rotation speed set at 250 revolutions / min. Then, the mixed material is granulated in a twin-screw extruder with a blending temperature set at 187 °C, a die head temperature set at 172 °C, and a screw extrusion rotation speed of 125 revolutions / min. After granulation, it is dried in an oven at 65 °C to obtain the special material for blow molding of the outer polyethylene film.

[0077] Put the special blowing material for the outer polyethylene film into the blown film machine, set the processing temperature to 187 °C, the blow-up ratio to 1.8, cool it with an air ring after forming, perform rotary traction after cooling, the traction ratio is 3.4, and then cut and wind it to obtain the outer protective film.

[0078] Preparation of bubble film:

[0079] First, put 100 parts by weight of low-density polyethylene, 12 parts by weight of low-density linear polyethylene, 15 parts by weight of 8401 ethylene-1-octene copolymer, 12 parts by weight of 3518CB metallocene linear low-density polyethylene, 3.5 parts by weight of citral, 2.5 parts by weight of quercetin, 1.5 parts by weight of ethoxylated fatty amine, 0.17 parts by weight of silica, 0.05 parts by weight of erucamide, and 2.5 parts by weight of illite into a blender, mix at room temperature for 22 min, set the rotation speed to 250 rpm, and then granulate the mixed material in a twin-screw extruder. Set the blending temperature to 172 °C, the die head temperature to 165 °C, and the screw extrusion speed to 125 rpm. After granulation, dry it in an oven at 52 °C to obtain the special material for the inner bubble film.

[0080] Put the obtained special material for the inner bubble film into the bubble film machine, the processing temperature is 192 °C, the rotation speed is set to 350 rpm, the extruded polyethylene is subjected to casting, vacuum adsorption by a bubble roller, and a bubble film is prepared. The vacuum degree of the bubble roller is 0.04 MPa, the bubble hole diameter is 9 mm, and the bubble height is 4 mm. After the bubble film is stably formed, introduce the prepared outer protective film into the machine through a traction roller and compound it with the bubble film. The outer protective film is compounded with the inner bubble film at the bubble roller, that is, while the bubble film is formed, it is pressed together with the outer protective film. Finally, after trimming and winding, a recyclable high-strength polyethylene antibacterial bubble film is obtained.

[0081] The test results are shown in Table 1.

[0082] Example

[0083] This example provides a method for preparing a recyclable high-strength antibacterial polyethylene bubble film, including:

[0084] Preparation of outer protective film:

[0085] First, place 100 parts by weight of high-density polyethylene, 3 parts by weight of ethylene-acrylic acid random copolymer, 1.5 parts by weight of hydrotalcite, 1.5 parts by weight of mica stone, 6 parts by weight of metallocene linear low-density polyethylene, 1 part by weight of citric acid ester, 1 part by weight of tributyl citrate, 2 parts by weight of eugenol, 2 parts by weight of thymol, 1.5 parts by weight of grape tannin, 1.5 parts by weight of curcumin, 1 part by weight of ethoxylated laurylamide, and 1 part by weight of glycerol monostearate in a blender and mix at room temperature for 25 min with the rotation speed set at 300 rpm. Then, granulate the mixed material in a twin-screw extruder with the blending temperature set at 190 °C, the die temperature set at 175 °C, and the screw extrusion speed at 150 rpm. After granulation, dry it in an oven at 70 °C to obtain the special material for blow molding of the outer polyethylene film.

[0086] Put the special material for blow molding of the outer polyethylene film into a blown film machine, set the processing temperature at 190 °C, the blow-up ratio at 2.1, cool it with an air ring after forming, perform rotational traction after cooling with a draw ratio of 3.7, and then cut and wind it up to obtain the outer protective film.

[0087] Preparation of bubble film:

[0088] First, place 100 parts by weight of low-density polyethylene, 15 parts by weight of low-density linear polyethylene, 10 parts by weight of 841, 10 parts by weight of ethylene-1-octene copolymer 8402, 7 parts by weight of 3518CB, 8 parts by weight of metallocene linear low-density polyethylene 3518GA, 2 parts by weight of eugenol, 2 parts by weight of thymol, 1.5 parts by weight of grape tannin, 1.5 parts by weight of curcumin, 1 part by weight of ethoxylated laurylamide, 1 part by weight of glycerol monostearate, 0.12 parts by weight of diatomaceous earth, 0.13 parts by weight of calcium sulfate, 0.05 parts by weight of erucamide, 0.05 parts by weight of stearamide, 1.5 parts by weight of hydrotalcite, and 1.5 parts by weight of mica stone in a blender and mix at room temperature for 25 min with the rotation speed set at 300 rpm. Then, granulate the mixed material in a twin-screw extruder with the blending temperature set at 175 °C, the die temperature set at 165 °C, and the screw extrusion speed at 150 rpm. After granulation, dry it in an oven at 55 °C to obtain the special material for the inner bubble film.

[0089] The obtained special material for the inner layer of bubble film is put into a bubble film machine. The processing temperature is 195°C, the rotation speed is set at 350 revolutions per minute. The extruded polyethylene is processed through casting, vacuum adsorption by a bubble roller, and then made into bubble film. The vacuum degree of the bubble roller is 0.04 MPa, the bubble hole diameter is 10 mm, and the bubble height is 5 mm. After the bubble film is stably formed, the prepared outer protective film is introduced into the machine through a traction roller and compounded with the bubble film. The outer protective film is compounded with the inner layer of bubble film at the bubble roller, that is, while the bubble film is formed, it is pressed together with the outer protective film. Finally, through trimming and winding, a recyclable high-strength polyethylene antibacterial bubble film is obtained.

[0090] The test results are shown in Table 1.

[0091] Example

[0092] This example provides a method for preparing a recyclable high-strength antibacterial polyethylene bubble film, including:

[0093] Preparation of the outer protective film:

[0094] First, 100 parts by weight of high-density polyethylene, 3.5 parts by weight of ethylene-acrylic acid random copolymer, 1.5 parts by weight of montmorillonite, 2 parts by weight of kaolin, 8 parts by weight of metallocene linear low-density polyethylene, 1 part by weight of tributyl citrate and 1.5 parts by weight of acetyl tributyl citrate, 2 parts by weight of isoeugenol and 2.5 parts by weight of apple peel polyphenols, 1.7 parts by weight of curcumin and 1.8 parts by weight of tocopherol, 1.2 parts by weight of ethoxylated laurylamide and 1.3 parts by weight of glycerol palmitate are placed in a blender and mixed at room temperature for 27 minutes, with the rotation speed set at 350 revolutions per minute. Then, the mixed material is granulated in a twin-screw extruder, the blending temperature is set at 192°C, the die head temperature is set at 177°C, and the screw extrusion rotation speed is 175 revolutions per minute. After granulation, it is dried in an oven at 75°C to obtain the special material for blow molding the outer polyethylene film.

[0095] The special material for blow molding the outer polyethylene film is put into a blown film machine. The processing temperature is set at 192°C, the blow-up ratio is 2.5, and after forming, it is cooled by an air ring. After cooling, it is subjected to rotary traction, and the traction ratio is 4.1. Then, it is cut and wound to obtain the outer protective film.

[0096] Preparation of the bubble film:

[0097] First, place 100 parts by weight of low-density polyethylene, 17 parts by weight of low-density linear 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, 9 parts by weight of 4518PA metallocene linear low-density polyethylene, 2 parts by weight of isoeugenol, 2.5 parts by weight of apple peel polyphenols, 1.7 parts by weight of curcumin, 1.8 parts by weight of tocopherol, 1.2 parts by weight of ethoxylated laurylamide, 1.3 parts by weight of glycerol palmitate, 0.17 parts by weight of diatomaceous earth, 0.17 parts by weight of calcium hydrogen phosphate, 0.07 parts of oleamide, 0.08 parts by weight of behenamide, 1.5 parts by weight of montmorillonite, and 2 parts by weight of kaolin in a blender, mix at room temperature for 27 min with a rotation speed set at 350 rpm. Then, granulate the mixed material in a twin-screw extruder with the blending temperature set at 177 °C, the die head temperature set at 167 °C, and the screw extrusion rotation speed at 175 rpm. After granulation, dry it in an oven at 57 °C to obtain the special material for the inner layer of bubble film.

[0098] Put the obtained special material for the inner layer of bubble film into a bubble film machine, with the processing temperature at 197 °C and the rotation speed set at 450 rpm. The extruded polyethylene is processed through casting, vacuum adsorption by a bubble roller, and made into bubble film. The vacuum degree of the bubble roller is 0.04 MPa, the bubble hole diameter is 11 mm, and the bubble height is 6 mm. After the bubble film is stably formed, introduce the prepared outer protective film into the machine through a traction roller and compound it with the bubble film. The outer protective film is compounded with the inner layer of bubble film at the bubble roller, that is, while forming the bubble film, it is pressed together with the outer protective film. Finally, through edge trimming and winding, a recyclable high-strength polyethylene antibacterial bubble film is obtained.

[0099] The test results are shown in Table 1.

[0100] Example

[0101] This example provides a method for preparing a recyclable high-strength antibacterial polyethylene bubble film, including:

[0102] Preparation of the outer protective film:

[0103] First, place 100 parts by weight of high-density polyethylene, 4 parts by weight of ethylene-acrylic acid random copolymer, 1 part by weight of hydrotalcite, 1 part by weight of illite, and 2 parts by weight of montmorillonite, 10 parts by weight of metallocene linear low-density polyethylene, 1 part by weight of tributyl citrate, 1 part by weight of acetyl tributyl citrate, and 1 part by weight of glyceryl triacetate, 1.5 parts by weight of citral, 1.5 parts by weight of allicin, and 2 parts by weight of thymol, 2 parts by weight of tocopherol, and 2 parts by weight of resveratrol, 1.5 parts by weight of ethoxylated laurylamide, and 1.5 parts by weight of glycerol-polyethylene glycol ester in a blender and mix at room temperature for 30 min with a rotation speed set at 400 rpm. Then, granulate the mixed material in a twin-screw extruder with a blending temperature set at 195 °C, a die head temperature set at 180 °C, and a screw extrusion speed of 2 hundred rpm. After granulation, dry it in an oven at 80 °C to obtain the special material for blow molding of the outer polyethylene film.

[0104] Put the special material for blow molding of the outer polyethylene film into a blown film machine, set the processing temperature at 195 °C, the blow-up ratio at 2.8. After forming, cool it with an air ring, and then perform rotary traction with a draw ratio of 4.5. Then, cut and wind it up to obtain the outer protective film.

[0105] Preparation of bubble film:

[0106] First, place 100 parts by weight of low-density polyethylene, 20 parts by weight of low-density linear polyethylene, 10 parts by weight of 8452 ethylene-1-octene copolymer, 10 parts by weight of DF740, 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, 1.5 parts by weight of citral, 1.5 parts by weight of allicin, and 2 parts by weight of thymol, 2 parts by weight of tocopherol, and 2 parts by weight of resveratrol, 1.5 parts by weight of ethoxylated laurylamide, and 1.5 parts by weight of glycerol-polyethylene glycol ester, 0.2 parts by weight of silica, and 0.2 parts by weight of calcium sulfate, 0.1 part of erucic acid amide, and 0.1 part by weight of isostearic acid amide, 1 part by weight of hydrotalcite, 1 part by weight of illite, and 2 parts by weight of montmorillonite in a blender and mix at room temperature for 30 min with a rotation speed set at 400 rpm. Then, granulate the mixed material in a twin-screw extruder with a blending temperature set at 180 °C, a die head temperature set at 170 °C, and a screw extrusion speed of 200 rpm. After granulation, dry it in an oven at 60 °C to obtain the special material for the inner bubble film.

[0107] The obtained special material for the inner layer of bubble film is put into a bubble film machine. The processing temperature is 200 °C, the rotation speed is set at 500 revolutions per minute. The extruded polyethylene is subjected to casting, vacuum adsorption by a bubble roller, and made into bubble film. The vacuum degree of the bubble roller is 0.04 MPa, the bubble hole diameter is 12 mm, and the bubble height is 7 mm. After the bubble film is stably formed, the prepared outer protective film is introduced into the machine through a traction roller and compounded with the bubble film. The outer protective film is compounded with the inner layer of bubble film at the bubble roller, that is, while the bubble film is formed, it is pressed together with the outer protective film. Finally, through trimming and winding, a recyclable high-strength polyethylene antibacterial bubble film is obtained.

[0108] The test results are shown in Table 1.

[0109] Comparative Example 1

[0110] Preparation of the outer protective film:

[0111] First, 100 parts by weight of high-density polyethylene and 0.5 part by weight of citric acid are placed in a mixer and mixed at room temperature for 20 min. The rotation speed is set at 200 revolutions per minute. Then, the mixed material is granulated in a twin-screw extruder. The blending temperature is set at 185 °C, the die head temperature is set at 170 °C, and the screw extrusion rotation speed is 100 revolutions per minute. After granulation, it is dried in an oven at 60 °C to obtain the special material for blow molding of the outer polyethylene film.

[0112] The special material for blow molding of the outer polyethylene film is put into a blown film machine. The processing temperature is set at 185 °C, the blow-up ratio is 1.5. After forming, it is cooled by an air ring. After cooling, it is subjected to rotary traction, and the draw ratio is 3.0. Then, it is cut and wound to obtain the outer protective film.

[0113] Preparation of bubble film:

[0114] First, 100 parts by weight of low-density polyethylene, 10 parts by weight of linear low-density polyethylene, 0.1 part by weight of talcum powder, and 0.01 part of oleic acid amide are placed in a mixer and mixed at room temperature for 20 min. The rotation speed is set at 200 revolutions per minute. Then, the mixed material is granulated in a twin-screw extruder. The blending temperature is set at 170 °C, the die head temperature is set at 160 °C, and the screw extrusion rotation speed is 100 revolutions per minute. After granulation, it is dried in an oven at 50 °C to obtain the special material for the inner layer of bubble film.

[0115] Put the obtained special material for inner-layer bubble film into the bubble film machine. The processing temperature is 190°C, the rotation speed is set at 300 revolutions per minute. The extruded polyethylene is processed through casting, vacuum adsorption by the bubble roller, and made into bubble film. The vacuum degree of the bubble roller is 0.04 MPa, the bubble hole diameter is 8 mm, and the bubble height is 3 mm. After the bubble film is stably formed, the prepared outer protective film is introduced into the machine through the traction roller and compounded with the bubble film. The outer protective film is compounded with the inner-layer bubble film at the bubble roller, that is, while the bubble film is formed, it is pressed together with the outer protective film. Finally, through trimming and winding, a recyclable high-strength polyethylene antibacterial bubble film is obtained.

[0116] The test results are shown in Table 1.

[0117] Table 1. Test Results

[0118]

[0119] It can be seen that in the present invention, ethylene-acrylic acid random copolymer is used as a compatibilizer and synergistically modified with inorganic fillers to prepare a high-strength outer protective film of high-density polyethylene, while increasing the strength and toughness of high-density polyethylene.

[0120] The present invention uses metallocene low-density polyethylene and ethylene-α-olefin elastomer to synergistically modify the low-density polyethylene bubble film. Through the organic combination of different molecular structures, the molecular chain segments are entangled with each other, and the interlayer compatibility is improved.

[0121] The present invention uses all polyvinyl materials, which can improve the comprehensive mechanical properties of the bubble film while the product can be recycled and reused.

[0122] The present invention uses bio-based extracts as antibacterial agents and antioxidants to functionalize and modify the bubble film. The antibacterial effect is lasting and effective, and the processing aids used are all non-toxic and harmless materials.

[0123] The above is only the preferred embodiment of the present invention, and it is not a limitation to any form and essence of the present invention. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the method of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. For those skilled in the art, without departing from the spirit and scope of the present invention, any equivalent changes made by using the technical content disclosed above, such as minor modifications, decorations and evolutions, are all equivalent embodiments of the present invention; at the same time, any equivalent changes made to the above embodiments based on the essential technology of the present invention, such as modifications, decorations and evolutions, still fall within the scope of the technical solution of the present invention.

Claims

1. A recyclable high-strength antibacterial polyethylene bubble film, characterized in that, The high-strength antibacterial polyethylene bubble film comprises an outer protective film and an inner polyethylene bubble film. The raw materials of the outer protective film include, by weight parts: 100 parts of high-density polyethylene, 2-4 parts of compatibilizer, 2-4 parts of inorganic filler, 2-10 parts of metallocene linear low-density polyethylene, 1-3 parts of plasticizer, 3-5 parts of antibacterial agent, 2-4 parts of antioxidant and 1-3 parts of antistatic agent; The raw materials of the inner polyethylene bubble film include: 100 parts of low-density polyethylene, 10-20 parts of low-density linear polyethylene, 10-30 parts of ethylene-α-olefin elastomer, 10-20 parts of metallocene linear low-density polyethylene, 3-5 parts of antibacterial agent, 2-4 parts of antioxidant, 1-3 parts of antistatic agent, 0.1-0.4 parts of opening agent, 0.01-0.2 parts of slip agent and 2-4 parts of inorganic filler; The compatibilizer is ethylene-acrylic acid random copolymer; The antibacterial agent is one or more of cinnamaldehyde, citral, eugenol, isoeugenol, thymol, apple peel polyphenols, allicin, vanillin; The antioxidant is one or more of tea polyphenols, quercetin, grape tannin, curcumin, tocopherol, resveratrol.

2. The recyclable high-strength antibacterial polyethylene bubble film according to claim 1, wherein Among the raw materials of the outer protective film, the density of the high-density polyethylene is 0.941-0.965 g / cm3, and the melt index is 2.0-3.0 g / 10 min; The acrylic acid content in the ethylene-acrylic acid random copolymer is 6-10%, and the melt index is 3-5 g / 10 min.

3. A recyclable high-strength antibacterial polyethylene bubble film according to claim 1, characterized in that, Among the raw materials of the inner polyethylene bubble film, the density of the low-density polyethylene is 0.910-0.925 g / cm3, and the melt index is 4.0-5.0 g / 10 min; The density of the low-density linear polyethylene is 0.918-0.930 g / cm3, and the melt index is 3.0-5.0 g / 10 min; The ethylene-α-olefin elastomer is an elastomer obtained by random copolymerization of ethylene and 1-butene or 1-octene, and the melt index is 2.0-20.0 g / 10 min.

4. The recyclable high-strength antibacterial polyethylene bubble film according to claim 3, wherein The ethylene-α-olefin elastomer is one or more of 8200, 8401, 8402, 8411 and 8452 ethylene-1-octene random copolymers and 7256, DF740, DF8200, DF140 and A4085s ethylene-1-butene random copolymers.

5. A recyclable high-strength antibacterial polyethylene bubble film according to claim 1, characterized in that, The metallocene linear low density polyethylene is a linear low density polyethylene obtained by copolymerizing ethylene with a small amount of higher olefins under metallocene catalysis, with a melt index of 2 - 5 g / 10 min and a density of 0.910 - 0.927 g / cm 3 .

6. A recyclable high-strength antibacterial polyethylene bubble film according to claim 5, characterized in that, The metallocene linear low-density polyethylene is one or more of 2718CB, 3518CB, 3518GA, 4518PA metallocene linear low-density polyethylene.

7. A recyclable high-strength antibacterial polyethylene bubble film according to claim 1, wherein, The antistatic agent is one or more of ethoxylated laurylamide, ethoxylated fatty amine, glycerol-stearate, glycerol-palmitate, glycerol-polyethylene glycol ester; The inorganic filler is one or more of hydrotalcite, illite, muscovite, montmorillonite, kaolin, and the average particle size is 200-400 nm; The plasticizer is one or more of citrate ester, tributyl citrate, acetyl tributyl citrate, triacetin; The anti-blocking agent is one or more of talcum powder, silica, calcium sulfate, calcium hydrogen phosphate and diatomaceous earth, and the particle size of the anti-blocking agent is 50-200 nm; The slip agent is one or more of oleic acid amide, erucic acid amide, behenic acid amide, stearic acid amide and isostearic acid amide.

8. A method for preparing a recyclable high-strength antibacterial polyethylene bubble film according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: 1) Preparation of the outer protective film: Put high-density polyethylene, compatibilizer, inorganic filler, metallocene linear low-density polyethylene, plasticizer, bacteriostat, antioxidant and antistatic agent in a blender according to the formula amount, and granulate the mixed materials in a twin-screw extruder; after granulation, dry them to obtain the special material for the outer protective film; Put the special material for the outer protective film into a blown film machine, cool it with an air ring after forming, perform rotary traction after cooling, cut and wind it to obtain the outer protective film; 2) Preparation of the bubble film: Put low-density polyethylene, low-density linear polyethylene, ethylene-α-olefin elastomer, metallocene linear low-density polyethylene, bacteriostat, antioxidant, antistatic agent, anti-blocking agent, slip agent and inorganic filler in a blender according to the formula amount, and granulate the mixed materials in a twin-screw extruder; after granulation, dry them to obtain the special material for the inner bubble film; 3) Put the obtained special material for the inner bubble film into a bubble film machine, extrude the polyethylene through casting, vacuum adsorption by a bubble roller, and prepare a bubble film. After the bubble film is stably formed, introduce the prepared outer protective film into the machine through a traction roller and compound it with the bubble film; the outer protective film is compounded with the inner bubble film at the bubble roller, that is, while forming the bubble film, it is pressed together with the outer protective film; finally, after trimming and winding, a recyclable high-strength polyethylene antibacterial bubble film is obtained.

9. The preparation method of the recyclable high-strength antibacterial polyethylene bubble film according to claim 8, characterized in that, In step 1), the stirring conditions are mixing for 20-30 min at room temperature, and the rotation speed is 200-400 rpm; during granulation, the blending temperature is 185-195 °C, the die head temperature is 170-180 °C, and the screw extrusion rotation speed is 100-200 rpm; the drying temperature after granulation is 60-80 °C; the processing temperature of the blown film machine is 185-195 °C, and the blow-up ratio is 1.5-2.8; the traction ratio during rotary traction is 3.0-4.

5.

10. The preparation method of the recyclable high-strength antibacterial polyethylene bubble film according to claim 8, characterized in that, In step 2), the stirring conditions are mixing for 20-30 min at room temperature, and the rotation speed is set to 200-400 rpm; during granulation, the blending temperature is 170-180 °C, the die head temperature is 160-170 °C, and the screw extrusion rotation speed is 100-200 rpm; the drying temperature after granulation is 50-60 °C; the processing temperature of the bubble film machine is 190-200 °C, and the rotation speed is set to 300-500 rpm; the vacuum degree of the bubble roller is 0.04 MPa, the bubble hole diameter is 8-12 mm, and the bubble height is 3-7 mm.

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