Ultralow-temperature single PE (polyethylene) recoverable composite packaging film and preparation process thereof

Abstract

The invention relates to the technical field of functional packaging films, and discloses an ultralow-temperature single-PE recoverable composite packaging film and a preparation process thereof, and the preparation process comprises the following steps: preparing a monoepoxy monoethyoxyl hexaphenyl POSS (Polyhedral Oligomeric Silsesquioxane) compound; the preparation method comprises the following steps: carrying out surface modification treatment on a multi-walled carbon nanotube by using a single-epoxy-group single-ethyoxyl hexaphenyl POSS compound to prepare a single-epoxy-group POSS modified multi-walled carbon nanotube; the preparation method comprises the following steps: carrying out amino-epoxy ring-opening reaction on an amino functional group of bis (3-aminopropyl) terminated poly (dimethyl siloxane) and an epoxy functional group on the surface of a single epoxy POSS modified multi-walled carbon nanotube to prepare a composite modified component; the ultralow-temperature single PE recoverable composite packaging film is prepared by taking polyethylene resin as a single raw material, adding a composite modified component and adopting an eleven-layer co-extrusion blow molding film forming process, has more excellent barrier property, mechanical property and low-temperature resistance, is convenient to recycle and accords with the environment-friendly trend.

Description

Technical Field

[0001] The 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] At present, most plastic flexible packaging is made of films of different materials tightly bonded together by glue. For example, one of the composite packaging structures of rice is BOPA film / adhesive / PE film. The demand and output of packaging materials are increasing, but it is not easy to classify and recycle multi-material composite packaging after it is discarded after the packaging life cycle. At present, there is still no effective method to classify and recycle composite packaging materials of different materials.

[0003] Therefore, it is of great industrial value to research and develop packaging structures that have excellent barrier properties and puncture resistance and meet market demand and environmental protection trends.

[0004] Polyethylene (PE) film has many advantages such as excellent low temperature resistance, toughness, tensile strength and elongation, transparency, easy heat sealing and high cost performance, and is widely used in packaging materials such as food, medicine, and electronic products. However, polyethylene film is very sensitive to environmental stress (chemical and mechanical effects), that is, when facing changes in the external environment, such as temperature changes, mechanical stress, etc., it is easy to age, resulting in a decrease in its performance.

[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 MWCNTS surface has strong hydrophobicity and strong van der Waals forces between 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 composite materials.

[0006] In addition, polydimethylsiloxane can increase the flexibility of plastics, making them more plastic when used 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 invention combines multi-walled carbon nanotubes (MWCNTS) with a large aspect ratio and nanometer size effect with polydimethylsiloxane (PDMS) through cage-shaped polysilsesquioxane (POSS) to obtain a composite modified component, and utilizes the composite modified component to improve the mechanical properties, barrier properties, low temperature resistance and other properties of a multi-layer co-extruded polyethylene film, thereby preparing a composite packaging film, which adopts a single PE material for easy recycling and cyclic utilization, and conforms to the trend of environmental protection.

[0010] A preparation process of an ultra-low temperature single PE recyclable composite packaging film comprises the following steps:

[0011] Step 1: preparing a monoepoxy monoethoxy hexaphenyl POSS compound;

[0012] Step 2: The Si-OH functional group obtained by hydrolyzing the ethoxy group of the mono-epoxy mono-ethoxy hexaphenyl POSS compound undergoes a dehydration condensation reaction with the -OH functional group of the hydroxylated multi-walled carbon nanotube, and the mono-epoxy mono-ethoxy hexaphenyl POSS compound is modified on the surface of the multi-walled carbon nanotube to prepare a mono-epoxy POSS modified multi-walled carbon nanotube;

[0013] Step 3: preparing a composite modified component by reacting the amino functional group of the bis(3-aminopropyl)-terminated poly(dimethylsiloxane) with the epoxy functional group on the surface of the monoepoxy POSS-modified multi-walled carbon nanotube through an amino-epoxy ring-opening reaction;

[0014] Step 4: Using polyethylene resin as a single raw material, adding a composite modified component, designing the film structure of the eleven-layer co-extrusion film, the formula and dosage of each film layer, and adopting an eleven-layer co-extrusion blow molding film forming process to prepare an ultra-low temperature single PE recyclable composite packaging film.

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

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

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

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

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

[0020] The fifth 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;

[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 to 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 95-99wt% low-density polyethylene resin and 1-5wt% composite modified component, and the amount is 5-15 parts by weight.

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

[0028] Step S3-1: using trihydroxyheptaphenyl 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 a vertex-opening method;

[0030] Step S3-3: Using intermediate b as a raw material and tetraethyl silicate as a capping agent, a monoepoxy monoethoxy hexaphenyl 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 eleven screw extruders of an eleven-layer co-extrusion film blow molding unit, after stirring and mixing, the molten resin is converged at the head of the machine through a diverter, and is extruded and blow-molded through a die head, the blow ratio is controlled at 2.5 to 2.9, cooled and wound, to prepare a composite packaging film with a thickness of 50 to 150 μm.

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

[0033] Preferably, the hydroxylated multi-walled carbon nanotubes have a diameter of 10 to 30 nm and a length of 5 to 20 μm.

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

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

[0036] Beneficial effects:

[0037] The present invention synthesizes a monoepoxy monoethoxy hexaphenyl POSS compound, uses it as a connector, connects multi-walled carbon nanotubes and polydimethylsiloxane to obtain a composite modified component, and introduces the composite modified component into a single material PE co-extruded film to prepare a composite packaging film;

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

[0039] Figure 1 is the chemical structural formula of a monoepoxy monoethoxy hexaphenyl POSS compound;

[0040] Wherein, R is phenyl;

[0041] Figure 2 These are the performance test results of the composite packaging film. DETAILED DESCRIPTION

[0042] Embodiment 1:

[0043] The preparation of the composite modified component comprises the following steps:

[0044] Step 1: preparing a monoepoxy monoethoxy hexaphenyl POSS compound;

[0045] Step 2: The Si-OH functional group obtained by hydrolyzing the ethoxy group of the mono-epoxy mono-ethoxy hexaphenyl POSS compound undergoes a dehydration condensation reaction with the -OH functional group of the hydroxylated multi-walled carbon nanotube, and the mono-epoxy mono-ethoxy hexaphenyl POSS compound is modified on the surface of the multi-walled carbon nanotube to prepare a mono-epoxy POSS modified multi-walled carbon nanotube;

[0046] Step 3: preparing a composite modified component by reacting the amino functional group of the bis(3-aminopropyl)-terminated poly(dimethylsiloxane) with the epoxy functional group on the surface of the monoepoxy POSS-modified multi-walled carbon nanotube through an amino-epoxy ring-opening reaction;

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

[0048] (1) prepare monoepoxy monoethoxy hexaphenyl POSS compound, its preparation process is:

[0049] An intermediate a is prepared, and the preparation method thereof is as follows: trihydroxy heptaphenyl POSS is used as a raw material, 3-(2,3-epoxypropoxy)propyltrimethoxysilane is used as a capping agent, and the intermediate a is synthesized by a vertex-capping method, and 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 until all dissolved under the protection of nitrogen, and then placed in an ice-water bath and stirred for 30 min, and then 1.2 mL of 3-(2,3-epoxypropoxy)propyltrimethoxysilane is added dropwise to the three-necked flask, and the stirring is continued in the ice-water bath for 20 min, and then the reaction is stirred at room temperature for 7 days, and anhydrous methanol and acetonitrile are used for precipitation, filtration, washing, and vacuum drying to obtain an intermediate a;

[0050] Prepare intermediate b, the preparation method of which is: use intermediate a as a raw material, use trifluoromethanesulfonic acid as an opening agent, and synthesize intermediate b by a vertex-opening method, and the specific experimental steps are as follows: add 3.6g of intermediate a into a round-bottom flask, add 80mL of dichloromethane and 5.1g of trifluoromethanesulfonic acid thereto in sequence, stir at room temperature to react for 0.5h, filter after the reaction is completed, add 5A molecular sieve to absorb and remove residual trifluoromethanesulfonic acid, rotary evaporation to remove the solvent, wash with a saturated aqueous solution of ether, filter, and vacuum dry to obtain intermediate b;

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

[0052] The nuclear magnetic resonance hydrogen spectrum of the monoepoxy monoethoxy hexaphenyl POSS compound is characterized as follows: 1 HNMR (CDCl3, 400MHz) 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 ultrasonic treatment was performed for 10 min. 1 g of a mono-epoxy monoethoxy hexaphenyl POSS compound and 2 drops of glacial acetic acid were added to the beaker in turn, and the mixture was stirred at room temperature for 10 h, centrifuged, and washed repeatedly by centrifugation with anhydrous ethanol and deionized water in turn, and dried in vacuo to obtain mono-epoxy POSS-modified multi-walled carbon nanotubes.

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

[0055] Among them, hydroxylated multi-walled carbon nanotubes were purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., with specifications of: diameter 10-30 nm, length 5-20 μm;

[0056] The bis(3-aminopropyl)-terminated poly(dimethylsiloxane) is purchased from Aladdin Reagent Network with a product number of A189544 and a specification of average Mn-3000.

[0057] Embodiment 2:

[0058] The preparation of the composite packaging film comprises the following steps:

[0059] Step 1: Set the composite packaging film to an eleven-layer symmetrical film structure, and the formula and dosage of each film layer are as follows:

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

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

[0062] The third layer: the formula is 100wt% low-density polyethylene resin, the amount is 10 parts by weight;

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

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

[0065] The sixth layer: the formula is 95wt% low-density polyethylene resin and 5wt% composite modified component, the amount is 20 parts by weight;

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

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

[0068] Ninth layer: the formula is 100wt% low-density polyethylene resin, the amount is 10 parts by weight;

[0069] The tenth layer: the formula is 100wt% high-density polyethylene resin, the amount is 5 parts by weight;

[0070] Eleventh layer: the formula is 97wt% low-density polyethylene resin and 3wt% composite modified component, the amount is 10 parts by weight;

[0071] Step 2: Put the raw materials in step 1 into the hoppers of eleven screw extruders of the eleven-layer co-extrusion film blowing unit respectively, after stirring and mixing, the molten resin is merged at the head of the die through the splitter, and is extruded and blown through the die head, the blow-up ratio is controlled at 2.6, cooled, and rolled to obtain a composite packaging film with a thickness of 70 μm;

[0072] Among them, the process parameters of the eleven screw extruders were set as follows: the temperatures of zones 1-3 were 130°C, 160°C, and 180°C, respectively, the flow channel temperature was 175°C, and the speed was 30r / min;

[0073] Low-density polyethylene resin was purchased from Jiangsu Rantai Plastic Chemical Co., Ltd. with the brand name LD 150DW; high-density polyethylene resin was purchased from Dongguan Longhuang Plastic Raw Materials Co., Ltd. with the brand name FB5600; maleic anhydride grafted polyethylene resin was purchased from Dongguan Taotao Plastic Raw Materials Co., Ltd. with the brand name 4288; ethylene-vinyl alcohol copolymer resin was purchased from Guangzhou Best New Material Technology Co., Ltd. with the brand name ET3803RB.

[0074] Comparative Example:

[0075] Preparation of conventional polyethylene packaging film: Referring to the preparation experiment of composite packaging film, the only difference is that no composite modified component is used, and a conventional polyethylene packaging film is prepared, which is used as a comparative example.

[0076] Performance Test:

[0077] 1. Barrier performance test:

[0078] (1) Use a Y110 oxygen permeability tester to test the oxygen barrier properties of the sample in accordance with GB / T 1038-2000 and record the oxygen permeability of the sample;

[0079] (2) Use TC-03 water vapor transmission meter to test the water barrier properties of the sample in accordance with GB / T 1037-2021 and record the water vapor transmission rate of the sample;

[0080] 2. Mechanical properties test:

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

[0082] (2) After placing the 30 mm × 5 mm sample in a -30 °C refrigerator for 48 h, take it out and use the QYJ1251 notched sample machine and ZBC-4B liquid crystal plastic pendulum impact tester to perform the notched impact strength test;

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

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

[0085]

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

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

[0088] (2) The composite packaging film prepared by the present invention has a significantly improved notched impact strength under low temperature (-30°C) conditions compared to unmodified conventional polyethylene packaging film, showing excellent low temperature resistance.

Claims

1. A process for preparing an ultra-low temperature single PE recyclable composite packaging film, characterized in that: The following steps are involved: Step 1: Prepare a monoepoxy monoethoxy hexaphenyl POSS compound, the chemical structure of which is: Step 2: The Si-OH functional group obtained by hydrolyzing the ethoxy group of the mono-epoxy mono-ethoxy hexaphenyl POSS compound undergoes a dehydration condensation reaction with the -OH functional group of the hydroxylated multi-walled carbon nanotube, and the mono-epoxy mono-ethoxy hexaphenyl POSS compound is modified on the surface of the multi-walled carbon nanotube to prepare a mono-epoxy POSS modified multi-walled carbon nanotube; Step 3: preparing a composite modified component by reacting the amino functional group of the bis(3-aminopropyl)-terminated poly(dimethylsiloxane) with the epoxy functional group on the surface of the monoepoxy POSS-modified multi-walled carbon nanotube through an amino-epoxy ring-opening reaction; Step 4: Using polyethylene resin as a single raw material, adding a composite modified component, designing the film structure of the eleven-layer co-extrusion film, the formula and dosage of each film layer, and adopting an eleven-layer co-extrusion blow molding film forming process to prepare an ultra-low temperature single PE recyclable composite packaging film.

2. The process for preparing an ultra-low temperature single PE recyclable composite packaging film according to claim 1, characterized in that: The raw material formula of the composite packaging film is: First layer: the formula is 95-99wt% low-density polyethylene resin and 1-5wt% composite modified component, the amount is 5-15 parts by weight; The second layer: the formula is 100wt% high-density polyethylene resin, the amount is 3 to 10 parts by weight; The third layer: the formula is 100wt% low-density polyethylene resin, the amount is 5-15 parts by weight; The fourth layer: the formula is 100wt% maleic anhydride grafted polyethylene resin, the amount is 2 to 8 parts by weight; The fifth 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; 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; 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; The eighth layer: the formula is 100wt% maleic anhydride grafted polyethylene resin, the amount is 2 to 8 parts by weight; Ninth layer: the formula is 100wt% low-density polyethylene resin, the amount is 5 to 15 parts by weight; The tenth layer: the formula is 100wt% high-density polyethylene resin, the amount is 3 to 10 parts by weight; The eleventh layer: The formula is 95-99wt% low-density polyethylene resin and 1-5wt% composite modified component, and the amount 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 monoepoxy monoethoxy hexaphenyl POSS compound is: Step S3-1: using trihydroxyheptaphenyl POSS as a raw material and 3-(2,3-epoxypropoxy)propyltrimethoxysilane as a capping agent, intermediate a is synthesized by a vertex-capping method; Step S3-2: Using intermediate a as a raw material and trifluoromethanesulfonic acid as an opening agent, intermediate b is synthesized by a vertex-opening method; Step S3-3: Using intermediate b as a raw material and tetraethyl silicate as a capping agent, a monoepoxy monoethoxy hexaphenyl POSS compound is synthesized by a vertex-capping method.

4. The process for preparing an ultra-low temperature single PE recyclable composite packaging film according to claim 2, characterized in that: The preparation method of the composite packaging film is as follows: each layer of raw materials is respectively put into the hoppers of eleven screw extruders of an eleven-layer co-extrusion film blow molding unit, after stirring and mixing, the molten resin is converged at the head of the machine through a diverter, and is extruded and blow-molded through a die head, the blow ratio is controlled at 2.5-2.9, cooled, and rolled up to prepare a composite packaging film with a thickness of 50-150 μm.

5. The process for preparing an ultra-low temperature single PE recyclable composite packaging film according to claim 1, characterized in that: The mass ratio of hydroxylated multi-walled carbon nanotubes, monoepoxy monoethoxy hexaphenyl POSS compound and bis(3-aminopropyl) end-capped poly(dimethylsiloxane) in the composite modified 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 hydroxylated multi-walled carbon nanotube has a diameter of 10 to 30 nm and a length of 5 to 20 μm.

7. The process for preparing an ultra-low temperature single PE recyclable composite packaging film according to claim 5, characterized in that: The number average molecular weight of the bis(3-aminopropyl)-terminated poly(dimethylsiloxane) is 2000-5000.

8. An ultra-low temperature single PE recyclable composite packaging film prepared by the process according to any one of claims 1 to 6, characterized in that: Application of the composite packaging film in the field of low-temperature resistant packaging.

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