A recyclable high-barrier thin film coating preparation process

Abstract

The application relates to the technical field of research and development of coated high-barrier films, and discloses a preparation process of a coated recyclable high-barrier film, which comprises the following steps: preparing a urea-based POSS-based coupling agent; performing surface modification treatment on graphene oxide by using the urea-based POSS-based coupling agent to obtain urea-based POSS-based graphene; performing compounding of the urea-based POSS-based graphene and polyvinyl alcohol by means of hydrogen bond action of urea-based functional groups contained on the surface of the urea-based POSS-based graphene and hydroxyl functional groups of the polyvinyl alcohol to obtain a crosslinked graphene polyvinyl alcohol composite material; and dissolving the crosslinked graphene polyvinyl alcohol composite material to prepare a coating liquid, which is coated on the surface of a five-layer co-extrusion film made of single PE material to obtain the coated recyclable high-barrier film. The film coating has excellent barrier performance, and the single PE material is convenient for recycling and recycling, and can be applied in the packaging field.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of research and development of coated high-barrier thin films, in particular to a coating preparation process of a recyclable high-barrier thin film. BACKGROUND

[0002] With the increasing white pollution and the daily consumption of non-renewable resources such as oil, it has become a hot spot in the packaging field to prepare a new recyclable packaging material to replace traditional packaging materials. Polyethylene (PE) is a high polymer material with excellent low-temperature resistance, toughness, tensile strength and elongation. Polyethylene film is widely used in the fields of food, medicine and electronic product packaging materials. The single-material polyethylene film can be recycled without classification, and can achieve 100% recycling, gradually becoming a trend in the development of the packaging industry. However, the single-material polyethylene film has limited barrier properties and cannot meet the actual use requirements of packaging materials.

[0003] Polyvinyl alcohol (PVA) is an environmentally friendly material that is degradable, recyclable and has high barrier properties. In the prior art, it has been reported that polyvinyl alcohol is dissolved in water and coated on the surface of a packaging film to improve the barrier properties. In addition, graphene oxide (GO) has a large specific surface area and can be easily functionalized to improve the interfacial compatibility and interfacial force between the polymer matrix and the graphene oxide. Moreover, graphene oxide has a relatively high aspect ratio, which can provide a longer propagation path for permeable molecules, and is an ideal filler for improving the barrier properties of polymers. SUMMARY

[0004] The application combines graphene oxide with excellent barrier properties and polyvinyl alcohol through a urea-based POSS-based coupling agent independently developed by the application to obtain a new cross-linked graphene polyvinyl alcohol composite material. The composite material is made into a coating liquid and applied to the surface of a single-PE five-layer co-extruded film to prepare a thin film coating. The thin film coating has excellent barrier properties, and the single-PE material is convenient for recycling and recycling, which meets the environmental protection trend.

[0005] A preparation process of a coated recyclable high-barrier thin film, comprising the following steps:

[0006] Step 1: preparing a urea-based POSS-based coupling agent;

[0007] Step 2: the Si-OH functional groups obtained by hydrolysis reaction of the methoxy groups of the urea-based POSS-based coupling agent and the -OH functional groups carried by the graphene oxide undergo dehydration condensation reaction, the urea-based POSS-based coupling agent is modified on the surface of the graphene oxide, and a urea-based POSS-based graphene is prepared.

[0008] Step 3: Compounding the urea-based POSS-based graphene with the polyvinyl alcohol through hydrogen bonding between the urea-based functional groups on the surface of the urea-based POSS-based graphene and the hydroxyl functional groups of the polyvinyl alcohol to prepare a cross-linked graphene polyvinyl alcohol composite material;

[0009] Step 4: dissolving the cross-linked graphene polyvinyl alcohol composite material to prepare a coating liquid, which is then coated on the surface of a five-layer co-extruded film made of a single PE material to prepare a coated recyclable high-barrier film.

[0010] Preferably, the preparation method of the urea-based POSS-based coupling agent is:

[0011] Step S2-1: using trihydroxy heptaisobutyl POSS as a raw material and para-aminophenyltrimethoxysilane as a capping agent, synthesizing an aniline POSS-based monomer by a vertex-capping method;

[0012] Step S2-2: a urea-based POSS-based coupling agent is generated by a nucleophilic addition reaction between the isocyanate group of 3-isocyanatepropyltrimethoxysilane and the amino functional group of the phenylamino POSS-based monomer.

[0013] Preferably, the formula and dosage of each film layer of the five-layer co-extruded film made of a single PE material are as follows:

[0014] First layer: The formula is 50-70wt% low-density polyethylene resin and 30-50wt% linear low-density polyethylene resin), the amount is 20-40 parts by weight;

[0015] Second layer: The formula is 100wt% maleic anhydride grafted polyethylene resin, the amount is 3-8 parts by weight;

[0016] The third layer: the formula is 20-40wt% high-density polyethylene resin, 20-40wt% linear low-density polyethylene resin, 30-40wt% metallocene polyethylene resin and 1-10wt% ethylene-vinyl alcohol copolymer resin, the amount is 10-40 parts by weight;

[0017] The fourth layer: the formula is 100wt% maleic anhydride grafted polyethylene resin, the amount is 3 to 8 parts by weight;

[0018] The fifth layer: the formula is 50-70 wt% of low-density polyethylene resin and 30-50 wt% of linear low-density polyethylene resin, and the amount is 20-40 parts by weight.

[0019] Preferably, the preparation method of the coated recyclable high barrier film is:

[0020] Step S4-1: The single PE material five-layer co-extrusion film is sequentially cleaned by using a mixed solution composed of 0.5-1.5 parts by volume of ethanol and 1 part by volume of deionized water and deionized water for pretreatment;

[0021] Step S4-2: 0.5-5 parts by weight of the cross-linked graphene polyvinyl alcohol composite material is dissolved in a mixed solution composed of 7-10 parts by volume of deionized water and 1 part by volume of N,N-dimethylformamide to prepare a cross-linked graphene polyvinyl alcohol composite material coating solution;

[0022] Step S4-2: The cross-linked graphene polyvinyl alcohol composite material coating solution is uniformly applied to the surface of the single PE material five-layer co-extrusion film, and dried to obtain a coated recyclable high-barrier film.

[0023] Preferably, the mass ratio of the urea-based POSS coupling agent, graphene oxide and polyvinyl alcohol in the cross-linked graphene polyvinyl alcohol composite material is 1:(1-5):(5-15).

[0024] Preferably, the flake diameter of the graphene oxide is 1-3 µm, and the thickness is 1-2 nm.

[0025] According to the above process, a coated recyclable high-barrier film is prepared;

[0026] Preferably, the thickness of the single PE material five-layer co-extrusion film is 80-120 µm, and the coating thickness of the cross-linked graphene polyvinyl alcohol composite material is 5-15 µm.

[0027] Preferably, the oxygen transmission rate of the coated recyclable high-barrier film is (1.0-1.5) cm 3 / (m 2 ·24h·0.1MPa), and the water vapor transmission rate is (1.5-2.0) g / (m 2 ·24h).

[0028] Advantages:

[0029] The present application designs and synthesizes a urea-based POSS coupling agent, which performs surface modification treatment on graphene oxide through covalent bond action, and cross-linking and compounding with polyvinyl alcohol based on hydrogen bond action to prepare a cross-linked graphene polyvinyl alcohol composite material; finally, the cross-linked graphene polyvinyl alcohol composite material is made into a coating solution and coated on the surface of a single PE material five-layer co-extrusion film to prepare a coated recyclable high-barrier film;

[0030] Experiments show that: compared with the single PE material five-layer co-extrusion film, the coated recyclable high-barrier film prepared by the present application can significantly reduce the oxygen transmission rate and the water vapor transmission rate, and exhibits excellent barrier performance;

[0031] And it is found that the prepared coated recyclable high barrier film has slightly improved mechanical properties and can be applied in the packaging field. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Performance test results of the coated recyclable high barrier film. DETAILED DESCRIPTION

[0033] Experimental example:

[0034] A urea-based POSS coupling agent was prepared, and its synthesis route is as follows:

[0035]

[0036] Step one: using trihydroxy hepta-isobutyl POSS as raw material, using p-aminophenyl trimethoxysilane as capping reagent, a phenylamino POSS-based monomer was synthesized by vertex-capping method;

[0037] Step two: through the nucleophilic addition reaction between the isocyanate group of 3-isocyanate propyl trimethoxysilane and the amino functional group of the phenylamino POSS-based monomer, a urea-based POSS coupling agent was generated;

[0038] The specific experimental steps for preparing the urea-based POSS coupling agent are as follows:

[0039] 4.0g of trihydroxy hepta-isobutyl POSS and 40mL of anhydrous tetrahydrofuran were 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 30min, 10mL of anhydrous tetrahydrofuran solution containing 1.1g of p-aminophenyl trimethoxysilane was added dropwise to the three-necked flask. After continuing to stir in the ice water bath for 20min, the reaction was carried out at room temperature for 7 days. Then, anhydrous methanol and acetonitrile were used for sedimentation, filtration, washing and vacuum drying, respectively, to obtain the phenylamino POSS-based monomer;

[0040] 3.0g of the phenylamino POSS-based monomer, 0.7g of 3-isocyanate propyl trimethoxysilane and 40mL of anhydrous tetrahydrofuran were added to a three-necked flask, and stirred at 70℃ under the protection of nitrogen and mechanical stirring for 5h. After cooling to room temperature, anhydrous methanol was used for washing, and vacuum drying was carried out to obtain the urea-based POSS coupling agent;

[0041] The hydrogen nuclear magnetic resonance spectrum of the urea-based POSS coupling agent is as follows: 1H NMR (DMSO-d6, 400 MHz) δ: 0.57-0.59 (d, 14H), 0.65-0.69 (t, 2H), 0.92-0.94 (d, 42H), 1.53-1.60 (m, 2H), 1.69-1.79 (m, 7H), 3.14-3.19 (m, 2H), 3.57 (s, 9H), 6.53-6.56 (t, 1H), 7.40-7.61 (m, 4H), 8.87 (s, 1H).

[0042] Example 1:

[0043] Preparation of urea POSS-based graphene: the Si-OH functional groups obtained by hydrolysis of methoxyl groups of the urea POSS-based coupling agent and the -OH functional groups carried by the graphene oxide undergo dehydration condensation reaction, the urea POSS-based coupling agent is modified on the surface of the graphene oxide, and the urea POSS-based graphene is prepared;

[0044] The specific experimental steps for preparing the urea POSS-based graphene are as follows: under the protection of nitrogen and mechanical stirring, 2 g of the urea POSS-based coupling agent, 5 g of graphene oxide, 20 mL of deionized water and 30 mL of anhydrous ethanol are added into a round-bottom flask, the mixture is stirred at room temperature for 2 h, then 1 mL of ammonia water is added dropwise into the flask, the temperature is increased to 60°C, and the reaction is stirred for 4 h, then the product is washed with anhydrous ethanol, filtered, and vacuum dried to obtain the urea POSS-based graphene.

[0045] The graphene oxide is purchased from Nanjing Xianfeng Nanometer Material Co., Ltd., and has a specification of a flake diameter of 1-3 μm and a thickness of 1-2 nm.

[0046] Example 2:

[0047] Preparation of cross-linked graphene polyvinyl alcohol composite material: the urea functional groups contained on the surface of the urea POSS-based graphene and the hydroxyl functional groups of the polyvinyl alcohol undergo hydrogen bonding, the urea POSS-based graphene is compounded with the polyvinyl alcohol, and the cross-linked graphene polyvinyl alcohol composite material is prepared.

[0048] The specific experimental steps for preparing the cross-linked graphene polyvinyl alcohol composite material are as follows: 2 g of polyvinyl alcohol resin and 50 mL of deionized water are added into a three-necked flask, the temperature is increased to 90°C, and the polyvinyl alcohol is dissolved by stirring for 4 h to prepare a polyvinyl alcohol mother liquor, the temperature is cooled to 60°C, 0.7 g of the urea POSS-based graphene is added into the three-necked flask, the reaction is stirred at 60°C for 5 h, and the mixture is uniformly mixed to obtain the cross-linked graphene polyvinyl alcohol composite material.

[0049] The polyvinyl alcohol resin is purchased from Dongguan Yingxiang Plastic Raw Material Co., Ltd., and has a model number of 22-88.

[0050] Example 3:

[0051] The preparation of the coated recyclable high-barrier film includes three preparation steps, which are as follows:

[0052] Step one: five-layer co-extrusion film of single PE material is prepared, and the five-layer co-extrusion film of single PE material is designed as a five-layer symmetrical film structure, which is prepared by using a five-layer co-extrusion blowing film process, and the specific preparation process is as follows:

[0053] The raw materials of the first layer (the formula is 60wt% low-density polyethylene resin and 40wt% linear low-density polyethylene resin), the second layer (the formula is 100wt% maleic anhydride grafted polyethylene resin), the third layer (the formula is 30wt% high-density polyethylene resin, 30wt% linear low-density polyethylene resin, 35wt% metallocene polyethylene resin and 5wt% ethylene-vinyl alcohol copolymer resin), the fourth layer (the formula is 100wt% maleic anhydride grafted polyethylene resin) and the fifth layer (the formula is 60wt% low-density polyethylene resin and 40wt% linear low-density polyethylene resin) are respectively put into the hoppers of the five screw extruders of the five-layer co-extrusion film blowing machine set according to the mass ratio of 30:5:30:5:30, and after stirring and mixing, the molten resin is converged at the die head through the flow divider, extruded and blown through the die, the take-up speed is 6m / min, and the blow-up ratio is controlled at 2.6, so as to obtain the five-layer co-extrusion film of single PE material with a thickness of 100μm;

[0054] The five-layer co-extrusion film of single PE material is fixed on a wire frame, washed in an ethanol solution (the volume ratio of ethanol and deionized water is 1:1) for 2h, and then washed with deionized water and dried at 45℃ for standby use;

[0055] The process parameters of the screw extruders of the first, second, fourth and fifth layers are set as follows: the temperatures of the 1-3 zones are 130℃, 150℃ and 180℃ respectively, the flow channel temperature is 170℃, and the rotation speed is 30r / min;

[0056] The process parameters of the screw extruder of the third layer are set as follows: the temperatures of the 1-3 zones are 140℃, 170℃ and 190℃ respectively, the flow channel temperature is 185℃, and the rotation speed is 40r / min;

[0057] Step two: a cross-linked graphene polyvinyl alcohol composite coating solution is prepared, and the specific preparation process is as follows: 3g of cross-linked graphene polyvinyl alcohol composite, 45mL of deionized water and 5mL of N,N-dimethylformamide are mixed, heated to 95℃ and stirred until completely dissolved, cooled to room temperature, and a cross-linked graphene polyvinyl alcohol composite coating solution is obtained;

[0058] Step three: fix the single PE material five-layer co-extrusion film on the coating machine, use a 5 μm metering rod to evenly apply the cross-linked graphene polyvinyl alcohol composite material coating liquid on the surface of the single PE material five-layer co-extrusion film, and dry it in a 70℃ oven for 3 h to obtain a coated recyclable high-barrier film;

[0059] The low-density polyethylene resin (model LD 150DW) was purchased from Jiangsu Rantai Plastic Co., Ltd.; the linear low-density polyethylene resin (model 2045G) was purchased from Yuyao Hongyang Plastic Co., Ltd.; the metallocene polyethylene resin (model SP4020) was purchased from Dongguan Jinshixiang Plastic Raw Material Co., Ltd.; the high-density polyethylene resin (model FB5600) was purchased from Dongguan Longhang Plastic Raw Material Co., Ltd.; the ethylene-vinyl alcohol copolymer resin (model ET3803RB) was purchased from Guangzhou Best New Material Technology Co., Ltd.; and the maleic anhydride grafted polyethylene resin (model 4288) was purchased from Dongguan Taota Plastic Raw Material Co., Ltd.

[0060] Performance test:

[0061] I. Barrier property test:

[0062] (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;

[0063] (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;

[0064] II. Mechanical properties:

[0065] The mechanical properties of the sample were tested using an Instron 5565 universal tensile testing machine, and the specific test steps were as follows: the 150mm×20mm sample was fixed on the tensile testing machine, and the tensile test was carried out at a tensile rate of 5mm / min, and the longitudinal and transverse tensile strengths of the sample were recorded;

[0066] The above test results are shown in Table 1 below.

[0067] Table 1 Performance test results of coated recyclable high-barrier film

[0068]

[0069]

[0070] The test data in Table 1 were plotted to obtain Figure 1 Through comprehensive analysis of the above experimental results, the following conclusions can be drawn:

[0071] (1) Compared with the five-layer co-extrusion film made of single PE material, the coated recyclable high-barrier film prepared by the application can significantly reduce the oxygen transmission rate and the water vapor transmission rate, and exhibits excellent barrier performance;

[0072] (2) The coated recyclable high-barrier film prepared by the application also slightly improves the mechanical properties.

Claims

1. A process for the preparation of a coated recyclable high barrier film, characterized in that, It comprises the following steps: Step one: preparing urea-based POSS coupling agent, the chemical structural formula is: Step two: through the methoxy of urea-based POSS coupling agent hydrolysis reaction obtained Si-OH functional group and the -OH functional group contained in graphene oxide dehydration condensation reaction, the urea-based POSS coupling agent is modified on the surface of graphene oxide, and the urea-based POSS graphene is prepared; Step three: through the urea-based functional group contained in the surface of urea-based POSS graphene and the hydroxyl functional group of polyvinyl alcohol, the hydrogen bond is generated, the urea-based POSS graphene and polyvinyl alcohol are compounded, and the crosslinked graphene polyvinyl alcohol composite material is prepared; Step four: the crosslinked graphene polyvinyl alcohol composite material is dissolved to prepare coating liquid, which is coated on the surface of the single PE material five-layer co-extruded film, and the coated recyclable high barrier film is prepared.

2. The process for preparing a coated recyclable high barrier film according to claim 1, characterized in that, The preparation method of the urea-based POSS coupling agent is: Step S2-1: using trihydroxy seven isobutyl POSS as raw material, using p-aminophenyl trimethoxysilane as capping reagent, synthesizing phenylamino POSS monomer through vertex-capping method; Step S2-2: through the nucleophilic addition reaction of the isocyanate group of 3-isocyanate propyl trimethoxysilane and the amino functional group of phenylamino POSS monomer, the urea-based POSS coupling agent is generated.

3. The process for preparing a coated recyclable high barrier film according to claim 1, characterized in that, The formula and amount of each film layer of the single PE material five-layer co-extruded film are as follows: The first layer: the formula is 50-70wt% low density polyethylene resin and 30-50wt% linear low density polyethylene resin, and the amount is 20-40 parts by weight; The second layer: the formula is 100wt% maleic anhydride grafted polyethylene resin, and the amount is 3-8 parts by weight; The third layer: the formula is 20-40wt% high density polyethylene resin, 20-40wt% linear low density polyethylene resin, 30-40wt% metallocene polyethylene resin and 1-10wt% ethylene-vinyl alcohol copolymer resin, and the amount is 10-40 parts by weight; The fourth layer: the formula is 100wt% maleic anhydride grafted polyethylene resin, and the amount is 3-8 parts by weight; The fifth layer: the formula is 50-70wt% low density polyethylene resin and 30-50wt% linear low density polyethylene resin, and the amount is 20-40 parts by weight.

4. The process for preparing a coated recyclable high barrier film according to claim 1, characterized in that, The preparation method of the coated recyclable high barrier film is: Step S4-1: the single PE material five-layer co-extruded film is pretreated by using the mixed solution composed of 0.5-1.5 parts by volume of ethanol and 1 part by volume of deionized water and deionized water in sequence; Step S4-2: 0.5-5 parts by weight of crosslinked graphene polyvinyl alcohol composite material is dissolved in the mixed solution composed of 7-10 parts by volume of deionized water and 1 part by volume of N,N-dimethylformamide, and the crosslinked graphene polyvinyl alcohol composite material coating liquid is prepared; Step S4-2: the crosslinked graphene polyvinyl alcohol composite material coating liquid is evenly coated on the surface of the single PE material five-layer co-extruded film, and the coated recyclable high barrier film is obtained after drying.

5. The process for preparing a coated recyclable high barrier film according to claim 1, characterized in that, The mass ratio of the urea-based POSS coupling agent, the graphene oxide and the polyvinyl alcohol in the cross-linked graphene polyvinyl alcohol composite is 1:(1-5):(5-15).

6. The process for preparing a coated recyclable high barrier film according to claim 5, characterized in that, The flake diameter of the graphene oxide is 1-3 microns, and the thickness is 1-2 nanometers.

7. A coated recyclable high barrier film prepared according to the process of any one of claims 1-6, characterized in that, The thickness of the five-layer co-extrusion film made of single PE material is 80-120 microns, and the coating thickness of the cross-linked graphene polyvinyl alcohol composite is 5-15 microns.

8. The coated recyclable high barrier film according to claim 7, characterized in that, The oxygen transmission amount of the coated recyclable high-barrier film is (1.0-1.5) cm 3 / (m 2 ·24h·0.1MPa), and the water vapor transmission amount is (1.5-2.0) g / (m 2 ·24h).

9. Application of a coated recyclable high-barrier film prepared by the process according to any one of claims 1-6 in the packaging field.

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