An ultra-low temperature single PE recyclable composite packaging film and a preparation process thereof

Abstract

The application relates to the technical field of functional packaging films, and discloses an ultralow-temperature single-PE recyclable composite packaging film and a preparation process, which comprises the following steps: preparing a single epoxy group single ethoxy hexaphenyl POSS compound; performing surface modification treatment on multi-walled carbon nanotubes by using the single epoxy group single ethoxy hexaphenyl POSS compound to prepare single epoxy group POSS modified multi-walled carbon nanotubes; preparing a composite modified component by causing amino-epoxy ring-opening reaction of amino functional groups of bis(3-aminopropyl) terminated poly(dimethylsiloxane) and epoxy functional groups on the surface of the single epoxy group POSS modified multi-walled carbon nanotubes; and preparing an ultralow-temperature single-PE recyclable composite packaging film by using polyethylene resin as a single raw material, adding the composite modified component and adopting an eleven-layer co-extrusion blow molding film process, so that the ultralow-temperature single-PE recyclable composite packaging film has more excellent barrier properties, mechanical properties and low-temperature resistance, is convenient to recycle and utilize, and meets the environmental protection trend.

Description

Technical Field

[0001] The present invention relates to the technical field of functional packaging films, in particular to an ultra-low temperature single PE recyclable composite packaging film and a preparation process thereof. Background Art

[0002] Currently, most plastic flexible packaging is made from a combination of films made from different materials, glued together. For example, rice packaging often uses a composite structure consisting of BOPA film, adhesive, and PE film. While both the demand and production of packaging materials are increasing, the separation and recycling of these composite packaging at the end of their lifecycle is challenging. Currently, there is no effective method for separating and recycling composite packaging materials.

[0003] Therefore, researching and developing packaging structures that have excellent barrier properties and puncture resistance while meeting market demand and environmental protection trends has important industrial value.

[0004] Polyethylene (PE) film boasts numerous advantages, including excellent low-temperature resistance, toughness, tensile strength and elongation, transparency, heat-sealability, and cost-effectiveness. It is widely used as a packaging material for food, pharmaceuticals, and electronic products. However, PE film is highly sensitive to environmental stresses (chemical and mechanical). In other words, it is susceptible to aging when exposed to changes in the external environment, such as temperature fluctuations and mechanical stress, leading to performance degradation.

[0005] Multi-walled carbon nanotubes (MWCNTS) are widely used in polymers due to their excellent mechanical properties and thermal stability. Studies have shown that adding MWCNTS to polymers can improve the mechanical properties, barrier properties and thermal properties of composite materials, but the improvement effect of MWCNTS on polymers depends on the degree of its dispersion in the matrix. The surface of MWCNTS is highly hydrophobic and there are strong van der Waals forces between the tubes, which makes it easy for them to entangle and agglomerate to form bundles in the polymer matrix (especially hydrophilic or water-soluble polymers). Studies have found that grafting POSS to the surface of MWCNTS can enhance its dispersibility in the polymer matrix, thereby more effectively improving the performance of the composite material.

[0006] In addition, polydimethylsiloxane can increase the flexibility of plastics, making them more malleable during use and reducing their brittleness. Therefore, polydimethylsiloxane is widely used in flexible plastic products such as plastic packaging bags and plastic films.

[0007] The present invention cites the following references:

[0008] Zhejiang University's master's thesis "Synthesis and Characterization of Functionalized POSS Monomers" disclosed the chemical structure and preparation method of trihydroxyheptaphenyl POSS. Summary of the Invention

[0009] The application combines multi-walled carbon nanotubes (MWCNTS) with large aspect ratio and nanometer size effect with polydimethylsiloxane (PDMS) through cage-shaped polyhedral oligomeric silsesquioxane (POSS) to obtain a composite modified component, uses the composite modified component to improve the mechanical properties, barrier properties, low-temperature resistance and other properties of a multi-layer co-extrusion polyethylene film, and prepares a composite packaging film which is made of single PE material and is convenient for recycling and recycling, and meets the environmental protection trend.

[0010] A preparation process of an ultralow-temperature single-PE recyclable composite packaging film, comprising the following steps:

[0011] Step one: preparing a mono-epoxy mon-ethoxy hexaphenyl POSS compound;

[0012] Step two: preparing a mono-epoxy POSS modified multi-walled carbon nanotube by a dehydration condensation reaction between Si-OH functional groups obtained by hydrolysis of ethoxy groups of the mono-epoxy mon-ethoxy hexaphenyl POSS compound and -OH functional groups on the hydroxylated multi-walled carbon nanotube, and modifying the mono-epoxy mon-ethoxy hexaphenyl POSS compound on the surface of the multi-walled carbon nanotube;

[0013] Step three: preparing a composite modified component by an amino-epoxy ring-opening reaction between amino functional groups of bis(3-aminopropyl) terminated poly(dimethylsiloxane) and epoxy functional groups on the surface of the mono-epoxy POSS modified multi-walled carbon nanotube;

[0014] Step four: preparing the ultralow-temperature single-PE recyclable composite packaging film by using polyethylene resin as a single raw material, adding the composite modified component, designing a film structure of the eleven-layer co-extrusion film, a formula and a dosage of each film layer, and adopting an eleven-layer co-extrusion blow molding film process.

[0015] Preferably, the raw material formula of the composite packaging film is:

[0016] The first layer: the formula is 95-99wt% low-density polyethylene resin and 1-5wt% composite modified component, and the dosage is 5-15 parts by weight;

[0017] The second layer: the formula is 100wt% high-density polyethylene resin, and the dosage is 3-10 parts by weight;

[0018] The third layer: the formula is 100wt% low-density polyethylene resin, and the dosage is 5-15 parts by weight;

[0019] The fourth layer: the formula is 100wt% maleic anhydride grafted polyethylene resin, and the dosage is 2-8 parts by weight;

[0020] The fifth layer is made of 95-99 wt% low-density polyethylene resin and 1-5 wt% ethylene-vinyl alcohol copolymer resin, with an amount of 5-15 parts by weight.

[0021] The sixth layer: the formula is 90-99wt% low-density polyethylene resin and 1-10wt% composite modified component, the amount is 10-30 parts by weight;

[0022] The seventh layer: the formula is 95-99wt% low-density polyethylene resin and 1-5wt% ethylene-vinyl alcohol copolymer resin, the amount is 5-15 parts by weight;

[0023] The eighth layer: the formula is 100wt% maleic anhydride grafted polyethylene resin, the amount is 2 to 8 parts by weight;

[0024] Ninth layer: The formula is 100wt% low-density polyethylene resin, the amount is 5-15 parts by weight;

[0025] The tenth layer: the formula is 100wt% high-density polyethylene resin, the amount is 3 to 10 parts by weight;

[0026] The eleventh layer: The formula is 95-99 wt% of low-density polyethylene resin and 1-5 wt% of composite modified components, with an amount of 5-15 parts by weight.

[0027] Preferably, the preparation method of the monoepoxy monoethoxy hexaphenyl POSS compound is:

[0028] Step S3-1: using trihydroxy heptaphenyl POSS as a raw material and 3-(2,3-epoxypropoxy)propyltrimethoxysilane as a capping agent, intermediate a is synthesized by a vertex-capping method;

[0029] Step S3-2: Using intermediate a as a raw material and trifluoromethanesulfonic acid as an opening reagent, intermediate b is synthesized by the vertex-opening method;

[0030] Step S3-3: Using intermediate b as a raw material and tetraethyl silicate as a capping agent, a monoepoxymonoethoxyhexaphenyl POSS compound is synthesized by a vertex-capping method.

[0031] Preferably, the preparation method of the composite packaging film is: the raw materials of each layer are respectively put into the hoppers of the eleven screw extruders of the eleven-layer co-extrusion film blowing unit, after stirring and mixing, the molten resin is converged at the head of the machine through the diverter, and extruded and blown through the die head, the blow-up ratio is controlled at 2.5-2.9, cooled and wound, and a composite packaging film with a thickness of 50-150 μm is prepared.

[0032] Preferably, the mass ratio of the hydroxylated multi-walled carbon nanotubes, the mono-epoxy mono-ethoxyl hexaphenyl POSS compound and the bis(3-aminopropyl) terminated poly(dimethylsiloxane) in the composite modified component is (1-5):1:(1-10).

[0033] Preferably, the diameter of the hydroxylated multi-walled carbon nanotubes is 10-30 nm, and the length is 5-20 microns.

[0034] Preferably, the number average molecular weight of the bis(3-aminopropyl) terminated poly(dimethylsiloxane) is 2000-5000.

[0035] The application of the ultra-low-temperature single-PE recyclable composite packaging film prepared according to the above process in the field of low-temperature resistant packaging.

[0036] Advantages:

[0037] The mono-epoxy mono-ethoxyl hexaphenyl POSS compound is synthesized, the multi-walled carbon nanotubes and the polydimethylsiloxane are connected by taking the mono-epoxy mono-ethoxyl hexaphenyl POSS compound as a connecting agent to obtain a composite modified component, and the composite modified component is introduced into a single-material PE co-extrusion film to prepare a composite packaging film.

[0038] Compared with conventional polyethylene packaging films, the composite packaging film prepared by the application has more excellent barrier properties, mechanical properties and low-temperature resistance, and can be recycled and reused. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is the chemical structural formula of the mono-epoxy mono-ethoxyl hexaphenyl POSS compound.

[0040] wherein R is a phenyl group.

[0041] Figure 2 is the performance test result of the composite packaging film. DETAILED DESCRIPTION

[0042] Example 1:

[0043] The composite modified component is prepared, including the following steps:

[0044] Step one: preparing a mono-epoxy mono-ethoxyl hexaphenyl POSS compound;

[0045] Step two: the Si-OH functional groups obtained by the hydrolysis reaction of the ethoxyl groups of the mono-epoxy mono-ethoxyl hexaphenyl POSS compound and the -OH functional groups carried by the hydroxylated multi-walled carbon nanotubes undergo dehydration condensation reaction, the mono-epoxy mono-ethoxyl hexaphenyl POSS compound is modified on the surface of the multi-walled carbon nanotubes to prepare a mono-epoxy POSS modified multi-walled carbon nanotube.

[0046] Step three: through the amino functional groups of bis(3-aminopropyl) terminated poly(dimethylsiloxane) and the epoxy functional groups on the surface of the mono-epoxy POSS modified multi-walled carbon nanotubes, an amino-epoxy ring-opening reaction occurs, and a composite modified component is prepared;

[0047] The specific experimental steps for preparing the composite modified component are as follows:

[0048] (1) The mono-epoxy mono-ethoxyl hexaphenyl POSS compound is prepared, and the preparation process is as follows:

[0049] The intermediate a is prepared by using trihydroxy heptaphenyl POSS as a raw material and 3-(2,3-epoxypropoxy) propyl trimethoxysilane as a capping reagent through the vertex-capping method. The specific experimental steps are as follows: 4.7 g of trihydroxy heptaphenyl POSS and 30 mL of anhydrous tetrahydrofuran are added to a three-necked flask, and stirred at room temperature under the protection of nitrogen until completely dissolved. After stirring in an ice water bath for 30 min, 1.2 mL of 3-(2,3-epoxypropoxy) propyl trimethoxysilane is added dropwise to the three-necked flask. After stirring in an ice water bath for 20 min, the reaction is carried out at room temperature for 7 days. Anhydrous methanol and acetonitrile are used for sedimentation, filtration, and washing, respectively, and vacuum drying is performed to obtain the intermediate a;

[0050] The intermediate b is prepared by using the intermediate a as a raw material and triflic acid as an opening reagent through the vertex-opening method. The specific experimental steps are as follows: 3.6 g of the intermediate a is added to a round-bottom flask, and 80 mL of dichloromethane and 5.1 g of triflic acid are added thereto in sequence. The reaction is carried out at room temperature for 0.5 h. After the reaction is completed, filtration is performed, 5A molecular sieves are added to absorb the residual triflic acid, the solvent is removed by rotary evaporation, and the intermediate b is obtained by washing with a saturated aqueous solution of diethyl ether, filtration, and vacuum drying;

[0051] The mono-epoxy mono-ethoxyl hexaphenyl POSS compound is prepared by using the intermediate b as a raw material and tetraethyl silicate as a capping reagent through the vertex-capping method. The chemical structural formula is as shown in Figure 1 The specific experimental steps are as follows: 2.4 g of the intermediate b and 50 mL of anhydrous tetrahydrofuran are added to a three-necked flask, and stirred at room temperature under the protection of nitrogen until completely dissolved. Then, the three-necked flask is placed in an ice water bath, and 0.6 mL of tetraethyl silicate is slowly added dropwise to the three-necked flask. The reaction is carried out in the ice water bath for 30 min, and then the ice water bath is removed. The reaction is continued at room temperature for 4 h. The mono-epoxy mono-ethoxyl hexaphenyl POSS compound is obtained by using acetonitrile for sedimentation, filtration, and washing, and vacuum drying;

[0052] The nuclear magnetic resonance hydrogen spectrum of the mono-epoxy mono-ethoxyl hexaphenyl POSS compound is characterized as follows: 1 HNMR (CDCI3, 400 MHz) δ: 0.65-0.69 (t, 2H), 1.16-1.20 (t, 3H), 1.78-1.85 (m, 2H), 3.21-3.59 (m, 7H), 3.95-4.01 (m, 2H), 7.32-7.55 (m, 30H).

[0053] (2) Preparation of mono-epoxy POSS modified multi-walled carbon nanotubes: 2 g of hydroxylated multi-walled carbon nanotubes, 80 mL of anhydrous ethanol and 20 mL of deionized water were added to a beaker and ultrasonically treated for 10 min, 1 g of mono-epoxy mono-ethoxyl hexaphenyl POSS compound and 2 drops of glacial acetic acid were sequentially added to the beaker, and the reaction was stirred at room temperature for 10 h, centrifuged, and repeatedly washed with anhydrous ethanol and deionized water, and vacuum dried to obtain mono-epoxy POSS modified multi-walled carbon nanotubes;

[0054] (3) Preparation of a composite modified component: 5 g of bis(3-aminopropyl) terminated poly(dimethylsiloxane) and 100 mL of anhydrous tetrahydrofuran were added to a three-necked flask under the protection of nitrogen, and dissolved by heating to 40°C under mechanical stirring, then 3 g of mono-epoxy POSS modified multi-walled carbon nanotubes were added to the three-necked flask, and the reaction was refluxed at 70°C for 3 h, cooled to room temperature, and the solvent was removed by rotary evaporation, and vacuum dried to obtain a composite modified component;

[0055] The hydroxylated multi-walled carbon nanotubes were purchased from Jiangsu Xianfeng Nanometer Material Technology Co., Ltd., and had a specification of: diameter 10-30 nm, length 5-20 μm;

[0056] The bis(3-aminopropyl) terminated poly(dimethylsiloxane) was bis(3-aminopropyl) terminated poly(dimethylsiloxane) with a product number of A189544 purchased from Aladdin Reagent Co., Ltd., and had a specification of: average Mn ~ 3000.

[0057] Example 2:

[0058] Preparation of a composite packaging film, including the following steps:

[0059] Step one: the composite packaging film was set to be a symmetrical film structure with eleven layers, and the formula and amount of each film layer were as follows:

[0060] The first layer: the formula was 97 wt% low density polyethylene resin and 3 wt% composite modified component, and the amount was 10 parts by weight;

[0061] The second layer: the formula was 100 wt% high density polyethylene resin, and the amount was 5 parts by weight;

[0062] The third layer is made of 100wt% low density polyethylene resin, and the amount is 10 parts by weight;

[0063] The fourth layer is made of 100wt% maleic anhydride grafted polyethylene resin, and the amount is 5 parts by weight;

[0064] The fifth layer is made of 97wt% low density polyethylene resin and 3wt% ethylene-vinyl alcohol copolymer resin, and the amount is 10 parts by weight;

[0065] The sixth layer is made of 95wt% low density polyethylene resin and 5wt% composite modification component, and the amount is 20 parts by weight;

[0066] The seventh layer is made of 97wt% low density polyethylene resin and 3wt% ethylene-vinyl alcohol copolymer resin, and the amount is 10 parts by weight;

[0067] The eighth layer is made of 100wt% maleic anhydride grafted polyethylene resin, and the amount is 5 parts by weight;

[0068] The ninth layer is made of 100wt% low density polyethylene resin, and the amount is 10 parts by weight;

[0069] The tenth layer is made of 100wt% high density polyethylene resin, and the amount is 5 parts by weight;

[0070] The eleventh layer is made of 97wt% low density polyethylene resin and 3wt% composite modification component, and the amount is 10 parts by weight;

[0071] Step two: the raw materials in step one are respectively put into the hoppers of the eleven screw extruders of the eleven-layer co-extrusion film blowing machine set, after mixing by stirring, the molten resins are converged at the die head through the flow divider, extruded and blown through the die, the blowing ratio is controlled at 2.6, cooled and wound, to obtain a composite packaging film with a thickness of 70μm;

[0072] The process parameters of the eleven screw extruders are all set as follows: the temperatures of the first to third zones are 130℃, 160℃ and 180℃ respectively, the flow channel temperature is 175℃, and the rotating speed is 30r / min;

[0073] The low density polyethylene resin is purchased from Jiangsu Rantai Plastic Co., Ltd., and the model number is LD 150DW; the high density polyethylene resin is purchased from Dongguan Longhang Plastic Raw Material Co., Ltd., and the model number is FB5600; the maleic anhydride grafted polyethylene resin is purchased from Dongguan TaoTao Plastic Raw Material Co., Ltd., and the model number is 4288; the ethylene-vinyl alcohol copolymer resin is purchased from Guangzhou Best New Material Technology Co., Ltd., and the model number is ET3803RB.

[0074] Comparative example:

[0075] Preparation of conventional polyethylene packaging film: refer to the preparation experiment of the composite packaging film, the difference is only that the composite modification component is not used, and the conventional polyethylene packaging film is prepared as a comparative example.

[0076] Performance test:

[0077] I. Barrier property test:

[0078] (1) The oxygen barrier property of the sample was tested using a Y110 oxygen transmission tester according to GB / T 1038-2000, and the oxygen transmission amount of the sample was recorded;

[0079] (2) The water vapor transmission of the sample was tested using a TC-03 water vapor transmission tester according to GB / T 1037-2021, and the water vapor transmission amount of the sample was recorded;

[0080] II. Mechanical property test:

[0081] (1) The notched impact strength of the sample was tested using a QYJ1251 notched sample machine and a ZBC-4B liquid crystal type plastic pendulum impact tester at 25°C, and the specific test steps were as follows: a 30mm×5mm sample was notched on the notched sample machine, the notch depth was 2mm, and the notch tip curvature radius was 0.25mm, and it was fixed on the pendulum impact tester for testing (the test temperature was 25°C), and the notched impact strength of the sample at room temperature was recorded;

[0082] (2) The 30mm×5mm sample was placed in a-30°C refrigerator for 48h, and then taken out and tested for notched impact strength using a QYJ1251 notched sample machine and a ZBC-4B liquid crystal type plastic pendulum impact tester;

[0083] The experimental results are shown in Table 1 and Figure 2 .

[0084] Table 1 Performance test results of the composite packaging film

[0085]

[0086] Through comprehensive analysis of the above experimental results, the following conclusions can be drawn:

[0087] (1) The composite modification component is introduced into the single material PE co-extruded film, and the composite packaging film prepared has excellent barrier property and mechanical property;

[0088] (2) The notched impact strength of the composite packaging film prepared by the present application at low temperature (-30°C) is significantly improved compared with the unmodified conventional polyethylene packaging film, and it shows excellent low temperature resistance.

Claims

1. A process for the preparation of an ultra-low temperature single PE recyclable composite packaging film, characterized by, The method comprises the following steps: Step 1: preparing a mono-epoxy mon-ethoxy hexa-phenyl POSS compound with a chemical structural formula as follows: Step 2: preparing a mono-epoxy POSS modified multi-walled carbon nanotube by carrying out a dehydration condensation reaction between Si-OH functional groups obtained by hydrolysis of an ethoxy group of the mono-epoxy mon-ethoxy hexa-phenyl POSS compound and -OH functional groups on the hydroxylated multi-walled carbon nanotube; Step 3: preparing a composite modified component by carrying out an amino-epoxy ring-opening reaction between amino functional groups of bis(3-aminopropyl) terminated poly(dimethylsiloxane) and epoxy functional groups on the surface of the mono-epoxy POSS modified multi-walled carbon nanotube; Step 4: preparing an ultra-low temperature single-PE recyclable composite packaging film by using a polyethylene resin as a single raw material, adding the composite modified component, designing a film structure of the eleven-layer co-extruded film, a formula and a dosage of each film layer, and adopting an eleven-layer co-extrusion blow molding process.

2. The process for the preparation of an ultra-low temperature single PE recyclable composite packaging film as claimed in claim 1, wherein, The raw material formula of the composite packaging film is as follows: The first layer: the formula is 95-99wt% low-density polyethylene resin and 1-5wt% composite modified component, and the dosage is 5-15 parts by weight; The second layer: the formula is 100wt% high-density polyethylene resin, and the dosage is 3-10 parts by weight; The third layer: the formula is 100wt% low-density polyethylene resin, and the dosage is 5-15 parts by weight; The fourth layer: the formula is 100wt% maleic anhydride grafted polyethylene resin, and the dosage is 2-8 parts by weight; The fifth layer: the formula is 95-99wt% low-density polyethylene resin and 1-5wt% ethylene-vinyl alcohol copolymer resin, and the dosage is 5-15 parts by weight; The sixth layer: the formula is 90-99wt% low-density polyethylene resin and 1-10wt% composite modified component, and the dosage is 10-30 parts by weight; The seventh layer: the formula is 95-99wt% low-density polyethylene resin and 1-5wt% ethylene-vinyl alcohol copolymer resin, and the dosage is 5-15 parts by weight; The eighth layer: the formula is 100wt% maleic anhydride grafted polyethylene resin, and the dosage is 2-8 parts by weight; The ninth layer: the formula is 100wt% low-density polyethylene resin, and the dosage is 5-15 parts by weight; The tenth layer: the formula is 100wt% high-density polyethylene resin, and the dosage is 3-10 parts by weight; The eleventh layer: the formula is 95-99wt% low-density polyethylene resin and 1-5wt% composite modified component, and the dosage is 5-15 parts by weight.

3. The process for preparing an ultra-low temperature single PE recyclable composite packaging film according to claim 1, characterized in that: The preparation method of the mono-epoxy mon-ethoxy hexa-phenyl POSS compound is as follows: Step S3-1: synthesizing an intermediate a by using trihydroxy hepta-phenyl POSS as a raw material and 3-(2,3-epoxypropoxy) propyl trimethoxysilane as a capping reagent through a vertex-capping method; Step S3-2: synthesizing an intermediate b by using trifluoromethanesulfonic acid as an opening reagent through a vertex-opening method with the intermediate a as a raw material; Step S3-3: synthesizing the mono-epoxy mon-ethoxy hexa-phenyl POSS compound by using tetraethyl silicate as a capping reagent through a vertex-capping method with the intermediate b as a raw material.

4. The process for the preparation of an ultra-low temperature single PE recyclable composite packaging film as claimed in claim 2, wherein, The preparation method of the composite packaging film is as follows: the raw materials of each layer are respectively put into the hoppers of eleven screw extruders of an eleven-layer co-extrusion film blowing machine set, after mixing by stirring, the molten resins are converged at the machine head through a flow divider, extruded and blown through a die, the blowing ratio is controlled at 2.5-2.9, and the composite packaging film with a thickness of 50-150 μm is prepared after cooling and winding.

5. The process for the preparation of an ultra-low temperature single PE recyclable composite packaging film as claimed in claim 1, wherein, The mass ratio of the hydroxylated multi-walled carbon nanotubes, the mono-epoxy mono-ethoxy hexaphenyl POSS compound and the bis(3-aminopropyl) terminated poly(dimethylsiloxane) in the composite modification component is (1-5):1:(1-10).

6. The process for preparing an ultra-low temperature single PE recyclable composite packaging film according to claim 5, characterized in that: The diameter of the hydroxylated multi-walled carbon nanotubes is 10-30 nm, and the length is 5-20 μm.

7. The process for the preparation of an ultra-low temperature single PE recyclable composite packaging film as claimed in claim 5 wherein, The number average molecular weight of the bis(3-aminopropyl) terminated poly(dimethylsiloxane) is 2000-5000.

8. A single PE recyclable composite packaging film prepared by the process according to any one of claims 1-6, characterized by, The application of the composite packaging film in the field of low-temperature resistant packaging.

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