An environmentally friendly high-barrier recyclable paper packaging film and its production process

Abstract

The invention relates to the technical field of paper packaging films, and discloses an environmentally friendly high-barrier recyclable paper packaging film and a manufacturing process thereof. The paper packaging film comprises an ink layer, a paper layer, and a barrier antibacterial layer from the outside to the inside. Polyvinyl alcohol is used as a film-forming substance for the barrier antibacterial layer, and the film has good gas barrier properties, excellent oil barrier properties, chemical corrosion resistance, and low cost. The invention prepares a high-barrier, antibacterial, and environmentally friendly barrier antibacterial layer by adding barrier substances and antibacterial substances to a polyvinyl alcohol matrix, prints a degradable water-based ink on the upper surface of base paper to form an ink layer, and uniformly coats the barrier antibacterial coating on the lower surface of the base paper by a coating process, and controls the coating amount to be 10-20 g / m 2 , dried at 50-70℃ for 4-6h to form a barrier antibacterial layer, and thus an environmentally friendly high-barrier recyclable paper packaging film can be obtained, which has superior performance and excellent application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of paper packaging films, in particular to an environmentally friendly high-barrier recyclable paper packaging film and a manufacturing process thereof. Background Art

[0002] Traditional high barrier packaging films include plastic and paper-plastic. Although plastic packaging films have the advantage of low price and are therefore widely used, providing great convenience in daily life, they will produce a large amount of non-degradable white pollutants after being abandoned, affecting the ecological balance, and consuming a large amount of non-renewable resources, resulting in a waste of resources. Paper-plastic packaging films are generally made of kraft paper, wood pulp paper, etc. as the main body of the film, combining the degradability and recyclability of paper with the superior properties of plastic such as shockproof. However, the preparation process of paper-plastic packaging films is relatively complicated, and some require adhesives to bond paper and plastic polymer materials. They also have poor antibacterial properties and poor barrier properties. Therefore, their application in food, daily chemicals and other fields is greatly limited, and paper-plastic packaging films need to be modified.

[0003] By coating the surface of base paper with a barrier and antibacterial coating and utilizing the performance advantages of the coating, the barrier and antibacterial properties of paper packaging film can be enhanced. Common environmentally friendly, recyclable, high-barrier materials for paper packaging film include: polyvinyl alcohol whose combustion products are only carbon dioxide and water, reusable polyethylene 2,6-naphthalate, and non-toxic silicon oxide ceramic coating. Among them, the cost of the synthetic raw materials of polyethylene 2,6-naphthalate is relatively high, and the technology of silicon oxide ceramic coating composite materials is relatively complex. Polyvinyl alcohol is biocompatible and a degradable material with good gas barrier properties, excellent oil resistance, wear resistance, chemical corrosion resistance, and low cost. Therefore, it can be used as a film-forming substance for the coating and can be combined with paper to form a packaging film without the need for an adhesive. However, the barrier and antibacterial properties of polyvinyl alcohol are poor and need to be improved.

[0004] Patent publication number CN112900148A discloses a method for improving the water vapor barrier properties of food packaging paper under high temperature and high humidity. Physically cross-linked polyvinyl alcohol / nanoclay / alkali lignin composite gel is coated on the surface of the paper, and the film-forming properties of polyvinyl alcohol are utilized. The stability of polyvinyl alcohol under high temperature and high humidity is improved by nanoclay and alkali lignin to form a dense layer on the surface of the paper. The method is simple, easy to operate, safe and environmentally friendly. However, the patent does not take into account the importance of the antibacterial properties of the paper packaging film, and there are still defects in practical applications. Therefore, the present invention proposes an environmentally friendly high-barrier recyclable paper packaging film and a production process thereof. Summary of the invention

[0005] The purpose of the present invention is to provide an environmentally friendly high-barrier recyclable paper packaging film and a production process thereof, which solves the following technical problems:

[0006] (1) The problem of poor barrier properties of polyvinyl alcohol-based coatings has been solved.

[0007] (2) The problem of poor antibacterial performance of polyvinyl alcohol-based coatings has been solved.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] An environmentally friendly high-barrier recyclable paper packaging film, the paper packaging film comprising an ink layer, a paper layer, and a barrier antibacterial layer from the outside to the inside;

[0010] The barrier antibacterial layer is formed by coating a barrier antibacterial coating on the lower surface of the paper layer;

[0011] The barrier antibacterial coating comprises the following raw materials in parts by weight: 40-60 parts of polyvinyl alcohol, 2-8 parts of barrier substances, 1-6 parts of antibacterial substances, 2-6 parts of glycerol, 50-60 parts of deionized water, and 1-3 parts of a crosslinking agent.

[0012] Furthermore, the preparation method of the barrier antibacterial material is as follows:

[0013] Add polyvinyl alcohol, barrier material, antibacterial material and glycerin into deionized water and stir evenly, then add cross-linking agent, heat to 90-100° C., stir for 1-2 hours, and obtain barrier antibacterial coating.

[0014] Furthermore, the preparation method of the barrier material comprises the following steps:

[0015] Step 1: adding micro-nano cellulose to tetrahydrofuran, ultrasonically dispersing for 5-10 minutes to form a uniform dispersion, introducing nitrogen, then adding acryloyl chloride and catalyst A, stirring at room temperature for 3-5 hours to obtain modified micro-nano cellulose;

[0016] Step 2: Place the modified micro-nano cellulose in anhydrous ethanol and stir evenly, add hydrogenated silicone oil, introduce nitrogen, heat to 70-80° C., stir for 10-15 minutes, add platinum catalyst, keep warm for 4-5 hours, and obtain a barrier material.

[0017] By adopting the above technical scheme, the active hydroxyl groups on the surface of micro-nano cellulose undergo esterification reaction with the acyl chloride structure in acryloyl chloride to obtain modified micro-nano cellulose. Under the action of a catalyst, the unsaturated olefins in the modified micro-nano cellulose structure can undergo addition reaction with the silicon-hydrogen bonds in the hydrogen-containing silicone oil to obtain a barrier substance.

[0018] Furthermore, in step 1, the catalyst A is triethylamine or pyridine.

[0019] Furthermore, in step 2, the hydrogen content of the hydrogen-containing silicone oil is 0.8%.

[0020] Furthermore, the method for preparing the antibacterial substance comprises the following steps:

[0021] Step A, adding soluble starch to a sodium hydroxide solution with a mass fraction of 45-50%, alkalizing for 2-4 hours, adding to anhydrous ethanol after alkalization, stirring at room temperature to form a uniform dispersion, passing nitrogen, adding catalyst B and 2-bromoethylamine hydrobromide, continuing to stir for 4-6 hours, filtering, centrifuging, and drying to obtain modified soluble starch;

[0022] Step B, adding the modified soluble starch to ethanol, stirring evenly at room temperature, then adding vanillin and acetic acid to the solution, heating to 80-90° C., stirring for 2-4 hours, cooling, filtering under reduced pressure, and drying to obtain an antibacterial substance.

[0023] By adopting the above technical scheme, the hydroxyl group in the soluble starch structure can undergo a substitution reaction with the bromine substituent in the 2-bromoethylamine hydrobromide structure, and an active amino group is introduced into the soluble starch to obtain a modified soluble starch. The active amino group in the modified soluble starch structure can undergo a Schiff base reaction with the aldehyde in the vanillin structure to obtain an antibacterial substance.

[0024] Furthermore, in step A, the catalyst B is triethylbenzylammonium chloride.

[0025] Furthermore, the cross-linking agent is any one of genipin, tannic acid or citric acid.

[0026] A process for producing an environmentally friendly high-barrier recyclable paper packaging film comprises the following steps:

[0027] The first step is to print the biodegradable water-based ink on the upper surface of the base paper to form an ink layer;

[0028] Step 2: Evenly apply the barrier antibacterial coating on the lower surface of the base paper, and control the coating amount to 10-20g / m 2 , dried at 50-70℃ for 4-6h to form a barrier antibacterial layer.

[0029] Furthermore, the base paper is kraft paper, wood pulp paper or glassine paper.

[0030] Beneficial effects of the present invention:

[0031] (1) After the barrier material prepared by the present invention is cross-linked with polyvinyl alcohol by the cross-linking agent, it can form a cross-linked network with polyvinyl alcohol. On the one hand, the existence of the cross-linked network can improve the density of the coating, thereby achieving the effect of water and gas barrier. At the same time, since the micro-nano cellulose in the barrier material has a strong interaction with the paper, it can fill the gaps on the surface of the paper, making the surface of the paper more uniform and smooth, and the roughness is reduced, thereby improving the barrier ability. After testing, the water vapor permeability is as low as 136g / (m 2 24h), the minimum oxygen permeability is 8.5cm 3 / (m 2 ·24h), on the other hand, the silicone oil in the barrier material structure has a lower surface energy, which can make the coating surface have a stronger hydrophobic effect, preventing water erosion from causing the coating to fall off. After testing, the maximum contact angle can reach 136.1°.

[0032] (2) The antibacterial substance of the present invention contains vanillin, which is a natural antibacterial substance with excellent antibacterial activity. The Schiff base structure produced at the same time can also play a good antibacterial effect, thereby enhancing the antibacterial property of the polyvinyl alcohol matrix. In the Escherichia coli inhibition zone test, the maximum inhibition diameter is 18.1 mm.

[0033] (3) The raw materials used in the present invention are all biodegradable, so the prepared paper packaging film has good biocompatibility, can be naturally degraded in the environment, and can also be recycled and reused. Therefore, it has good environmental protection and recyclability, which is beneficial to environmental protection and resource utilization.

[0034] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0036] Figure 1 Infrared schematic diagram of barrier material.

[0037] Figure 2 Infrared schematic diagram of antibacterial substances. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] The preparation process of barrier antibacterial coating includes the following steps:

[0041] 40g of polyvinyl alcohol, 2g of barrier material, 1g of antibacterial material and 2g of glycerol were added to 50g of deionized water and stirred evenly, and then 1g of genipin crosslinking agent was added, heated to 90°C, and stirred for 1h to obtain a barrier antibacterial coating;

[0042] The preparation process of the barrier material includes the following steps:

[0043] Step 1: 8 g of micro-nano cellulose was added to tetrahydrofuran, and ultrasonically dispersed for 5 min to form a uniform dispersion. Nitrogen was introduced, and then 10 g of acryloyl chloride and 0.5 g of triethylamine were added. The mixture was stirred at room temperature for 3 h to obtain modified micro-nano cellulose.

[0044] Step 2: Place 6 g of modified micro-nano cellulose in anhydrous ethanol and stir evenly, add 10 mL of hydrogen-containing silicone oil with a hydrogen content of 0.8%, pass nitrogen, heat to 75° C., stir for 10 min, add 1 μL of platinum catalyst, and keep warm for 4 h to obtain a barrier material.

[0045] The potassium bromide tablet method was used to prepare the sample, and the barrier material was tested by infrared using a Fourier transform infrared spectrometer, such as Figure 1 As shown, the spectral wavenumber test range is 4000cm -1 -500cm -1 , the analysis shows that in the infrared spectrum of modified micro-nanocellulose, 3022cm -1 The absorption peak of olefin carbon-hydrogen bond appeared at 1734 cm -1 The absorption peak of ester group appeared at 1093cm -1 The absorption peak of ether bond appears at 1043cm -1 The absorption peak of silicon-oxygen bond appears at 1093cm -1 The absorption peaks of the ether bonds overlap, 3022cm -1 The disappearance of the olefin carbon-hydrogen bond absorption peak at , indicates that the barrier material has been successfully prepared.

[0046] The preparation process of the antibacterial substance comprises the following steps:

[0047] Step A, adding 6 g of soluble starch to 4 mL of a 50% sodium hydroxide solution, alkalizing for 3 h, and then adding it to anhydrous ethanol, stirring at room temperature to form a uniform dispersion, passing nitrogen, adding 0.6 g of triethylbenzylammonium chloride and 7 g of 2-bromoethylamine hydrobromide, continuing to stir for 5 h, filtering, centrifuging, and drying to obtain modified soluble starch;

[0048] Step B: add 4 g of modified soluble starch to ethanol, stir evenly at room temperature, then add 3 g of vanillin and 2 mL of 20% acetic acid to the solution, heat to 80° C., stir for 3 h, cool, filter under reduced pressure, and dry to obtain an antibacterial substance.

[0049] The samples were prepared by potassium bromide tablet method and infrared test of antibacterial substances was performed by Fourier infrared spectrometer, such as Figure 2 As shown, the spectral wavenumber test range is 4000cm -1 -500cm -1 , analysis shows that in the infrared spectrum of modified soluble starch, 2925cm -1 The absorption peak of methylene appeared at 3428 cm -1 The absorption peak of amine group appears at 3428cm in the infrared spectrum of antibacterial substances. -1 The amine absorption peak at 1614 cm -1 The absorption peak of carbon-nitrogen double bond appeared at , indicating that the antibacterial substance was successfully prepared.

[0050] Example 2

[0051] The preparation process of barrier antibacterial coating includes the following steps:

[0052] 50 g of polyvinyl alcohol, 4 g of barrier material, 3 g of antibacterial material, and 3 g of glycerol were added to 55 g of deionized water and stirred evenly, and then 2 g of genipin crosslinking agent was added, heated to 95° C., and stirred for 1.5 h to obtain a barrier antibacterial coating;

[0053] The preparation process of the barrier material and the preparation process of the antibacterial material are the same as those in Example 1.

[0054] Example 3

[0055] The preparation process of barrier antibacterial coating includes the following steps:

[0056] Add 60g of polyvinyl alcohol, 6g of barrier material, 5g of antibacterial material, and 5g of glycerol to 60g of deionized water and stir evenly, then add 3g of genipin crosslinking agent, heat to 100°C, and stir for 2h to obtain a barrier antibacterial coating;

[0057] The preparation process of the barrier material and the preparation process of the antibacterial material are the same as those in Example 1.

[0058] Example 4

[0059] The preparation process of barrier antibacterial coating includes the following steps:

[0060] Add 60g of polyvinyl alcohol, 7g of barrier material, 6g of antibacterial material, and 65g of glycerol to 60g of deionized water and stir evenly, then add 3g of genipin crosslinking agent, heat to 100°C, and stir for 2h to obtain a barrier antibacterial coating;

[0061] Comparative Example 1

[0062] The preparation process of the antibacterial coating includes the following steps:

[0063] 50 g of polyvinyl alcohol, 3 g of antibacterial substance, and 3 g of glycerol were added to 55 g of deionized water and stirred evenly, and then 2 g of genipin crosslinking agent was added, heated to 95° C., and stirred for 1.5 h to obtain an antibacterial coating;

[0064] The preparation process of the antibacterial substance is the same as that in Example 1.

[0065] Comparative Example 2

[0066] The preparation process of barrier coating includes the following steps:

[0067] 50 g of polyvinyl alcohol, 4 g of barrier material, and 3 g of glycerol were added to 55 g of deionized water and stirred evenly, and then 2 g of genipin crosslinking agent was added, heated to 95° C., and stirred for 1.5 h to obtain a barrier coating;

[0068] The preparation process of the barrier material is the same as that in Example 1.

[0069] Comparative Example 3

[0070] The preparation process of the coating includes the following steps:

[0071] 50 g of polyvinyl alcohol, 4 g of micro-nanocellulose, 3 g of antibacterial substance, and 3 g of glycerol were added to 55 g of deionized water and stirred evenly, and then 2 g of genipin crosslinking agent was added, heated to 95° C., and stirred for 1.5 h to obtain a coating;

[0072] The preparation process of the antibacterial substance is the same as that in Example 1.

[0073] Performance Testing

[0074] The performance of the coatings prepared in Examples 1 to 4 of the present invention and Comparative Examples 1 to 3 was tested: the coating was applied on the surface of kraft paper and the performance was tested.

[0075] The kraft paper coated with the coating prepared in the embodiment and the comparative example was cut into samples of the same size, and the oxygen permeability of the samples was tested according to the GB / T19789-2021 standard, and the water vapor permeability of the samples was tested according to the GB / T 1037-2021 standard. 6 The suspension of CFU / mL Escherichia coli was evenly smeared on the sample, and the sample was placed in a culture dish and cultured at 37°C for 12 hours. The culture dish was taken out, and the diameter of the inhibition zone was measured with a vernier caliper to detect the antibacterial performance. The contact angle of the sample surface was measured using the OCA20 contact angle meter from Dataphys i cs, Germany. The test was carried out at room temperature, with a water drop volume of 2.0 μL, to measure the contact angle and detect the hydrophobicity. The test results are shown in the following table:

[0076]

[0077] As can be seen from the above table, the barrier antibacterial layers prepared in Examples 1 to 4 have excellent barrier properties, antibacterial properties and hydrophobic properties, among which Example 2 has the best test effect. No barrier substance is added in Comparative Example 1, and the water vapor permeability and oxygen permeability are relatively high. No antibacterial substance is added in Comparative Example 2, and the antibacterial diameter measurement value is relatively small. Micro-nano cellulose is added in Comparative Example 3, and the test results show that micro-nano cellulose can enhance the barrier properties to a certain extent. The materials used in the present invention are all recyclable environmentally friendly materials, and the prepared paper packaging film is recyclable and environmentally friendly.

[0078] An environmentally friendly high-barrier recyclable paper packaging film is prepared by using the barrier antibacterial coating prepared in Examples 1 to 4 of the present invention, and the preparation steps are as follows:

[0079] The first step is to print the Jiajing WPH series biodegradable ink on the surface of the base paper to form an ink layer;

[0080] Step 2: Evenly apply the barrier antibacterial coating on the lower surface of the base paper, and control the coating amount to 15g / m 2 , dried at 60°C for 5h to form a barrier antibacterial layer.

[0081] The above contents are merely examples and explanations of the concept of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. An environmentally friendly high barrier recyclable paper packaging film, characterized in that: The paper packaging film comprises an ink layer, base paper and a barrier antibacterial layer from the outside to the inside; The barrier antibacterial layer is formed by coating a barrier antibacterial coating on the lower surface of the base paper; The barrier antibacterial coating comprises the following raw materials in parts by weight: 40-60 parts of polyvinyl alcohol, 2-8 parts of barrier material, 1-6 parts of antibacterial material, 2-6 parts of glycerol, 50-60 parts of deionized water, and 1-3 parts of cross-linking agent; The preparation method of the barrier antibacterial coating is as follows: Add polyvinyl alcohol, barrier material, antibacterial material and glycerol into deionized water and stir evenly, then add crosslinking agent, heat to 90-100° C., stir for 1-2 hours to obtain barrier antibacterial coating; The method for preparing the barrier material comprises the following steps: Step 1: adding micro-nano cellulose to tetrahydrofuran, ultrasonically dispersing for 5-10 minutes to form a uniform dispersion, introducing nitrogen, then adding acryloyl chloride and catalyst A, stirring at room temperature for 3-5 hours to obtain modified micro-nano cellulose; Step 2: Place the modified micro-nano cellulose in anhydrous ethanol and stir evenly, add hydrogenated silicone oil, introduce nitrogen, heat to 70-80°C, stir for 10-15 minutes, add platinum catalyst, and keep warm for 4-5 hours to obtain a barrier material; The preparation method of the antibacterial substance comprises the following steps: Step A, adding soluble starch to a sodium hydroxide solution with a mass fraction of 45-50%, alkalizing for 2-4 hours, adding to anhydrous ethanol after alkalization, stirring at room temperature to form a uniform dispersion, passing nitrogen, adding catalyst B and 2-bromoethylamine hydrobromide, continuing to stir for 4-6 hours, filtering, centrifuging, and drying to obtain modified soluble starch; Step B, adding the modified soluble starch to ethanol, stirring evenly at room temperature, then adding vanillin and acetic acid to the solution, heating to 80-90° C., stirring for 2-4 hours, cooling, filtering under reduced pressure, and drying to obtain an antibacterial substance.

2. The environmentally friendly high barrier recyclable paper packaging film according to claim 1, characterized in that: In step 1, the catalyst A is triethylamine or pyridine.

3. The environmentally friendly high barrier recyclable paper packaging film according to claim 1, characterized in that: In step 2, the hydrogen content of the hydrogen-containing silicone oil is 0.8%.

4. The environmentally friendly high barrier recyclable paper packaging film according to claim 1, characterized in that: In step A, the catalyst B is triethylbenzylammonium chloride.

5. The environmentally friendly high barrier recyclable paper packaging film according to claim 1, characterized in that: The cross-linking agent is any one of genipin, tannic acid or citric acid.

6. A process for producing an environmentally friendly high barrier recyclable paper packaging film as claimed in claim 1, characterized in that: The following steps are involved: The first step is to print the biodegradable water-based ink on the upper surface of the base paper to form an ink layer; Step 2: Evenly apply the barrier antibacterial coating on the lower surface of the base paper, and control the coating amount to 10-20g / m 2 , dried at 50-70℃ for 4-6h to form a barrier antibacterial layer.

7. The process for producing the environmentally friendly high barrier recyclable paper packaging film according to claim 6, characterized in that: The base paper is kraft paper, wood pulp paper or glassine paper.

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