Antibacterial PE film for packaging bag and preparation method of antibacterial PE film

Abstract

The invention provides an antibacterial PE film for a packaging bag and a preparation method of the antibacterial PE film, and relates to the technical field of PE packaging bags, and the antibacterial PE film mainly comprises linear low density polyethylene, p-hydroxybenzoate, a nano-silver composite antibacterial agent, maleic anhydride grafted polyethylene, a plasticizer and a coupling agent. According to the antibacterial PE film, the components of the antibacterial PE film are improved, hydroxybenzoate can be uniformly distributed in the PE film to achieve the antibacterial effect, the nano-silver composite antibacterial agent is bonded in maleic anhydride grafted polyethylene in advance, and then the nano-silver composite antibacterial agent, linear low-density polyethylene, the plasticizer and the coupling agent are mixed, extruded, granulated and blow-molded to form the film, so that the antibacterial PE film is obtained. The nano-silver composite antibacterial agent and maleic anhydride grafted polyethylene are pre-mixed to obtain a high-viscosity intermediate, the nano content in the high-viscosity intermediate is high, the antibacterial effect is obvious, and the nano-silver composite antibacterial agent in the high-viscosity intermediate in the subsequent mixing process is high in stability and outstanding in antibacterial effect.

Description

Technical Field

[0001] The invention relates to the technical field of PE packaging bags, in particular to an antibacterial PE film for packaging bags and a preparation method thereof. Background Art

[0002] PE film is widely used in the packaging of various products due to its good physical properties and economy. The extensive use of PE film has brought great convenience to people's lives. In the field of food packaging, the shelf life of food also needs to be considered. The ventilation effect of the food in the contact area with the inside of the PE film is poor, which is easy to breed bacteria, thereby producing mucus and corroding / deteriorating the food. Therefore, the PE film used for food packaging has certain requirements for antibacterial properties.

[0003] However, the existing antibacterial PE film has insufficient antibacterial performance, which is mainly reflected in the poor stability of the antibacterial agent. The amount of antibacterial agent on the surface of the PE film is small and unstable, while the antibacterial agent in the inner layer of the PE film has little effect. In order to improve the antibacterial performance of the PE film, the present invention proposes a new antibacterial PE film and a preparation method thereof. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides an antibacterial PE film for packaging bags and a preparation method thereof, which solves the problem that the existing antibacterial PE film has insufficient antibacterial performance, which is mainly reflected in the poor stability of the antibacterial agent, the small and unstable amount of antibacterial agent on the surface of the PE film, and the little effect of the antibacterial agent in the inner layer of the PE film.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] An antibacterial PE film for packaging bags mainly comprises, by weight, 70-80 parts of linear low-density polyethylene, 1-1.2 parts of p-hydroxybenzoate, 2-8 parts of nano-silver composite antibacterial agent, 2-5 parts of maleic anhydride grafted polyethylene, 1-3 parts of plasticizer and 1-3 parts of coupling agent.

[0007] Preferably, the preparation method of the maleic anhydride grafted polyethylene is: setting the temperature of a twin-screw extruder at 140° C. to 220° C., and using the twin-screw extruder to melt-graft maleic anhydride into high-density polyethylene to obtain the maleic anhydride grafted polyethylene;

[0008] The amount of maleic anhydride used is 20%-35% by weight.

[0009] Further preferably, the preparation method of the nano silver composite antibacterial agent is:

[0010] Step 1: preparing a tea polyphenol solution with a concentration of 15-25 g / ml, then adding nano silver particles to the tea polyphenol solution at a ratio of 15-45 g / ml, and stirring to obtain a solid-liquid mixture;

[0011] Step 2: pour the solid-liquid mixture into a crucible for evaporation until the solid-liquid mixture is completely evaporated to dryness, and grind and sieve the obtained solid matter to obtain a nano-silver composite antibacterial agent.

[0012] More preferably, the weight ratio of tea polyphenols to nano-silver particles in the nano-silver composite antibacterial agent is 1:1-3.

[0013] Preferably, the plasticizer is one or more of dioctyl phthalate, dibutyl phthalate, tricresyl phosphate, and triphenyl phosphate.

[0014] Preferably, the coupling agent is one or more of γ-aminopropyltriethoxysilane and isopropyl triisostearate titanate.

[0015] A method for preparing an antibacterial PE film for packaging bags, comprising the following steps:

[0016] S1. Premixing the nano-silver composite antibacterial agent and maleic anhydride grafted polyethylene in a mixing tank at 220° C.-260° C. to obtain a highly viscous intermediate;

[0017] S2, preliminarily mixing the high-viscosity intermediate, linear low-density polyethylene, paraben, plasticizer, and coupling agent at a temperature of 160° C.-210° C., and then feeding into a twin-screw extruder for extrusion granulation to obtain raw material particles;

[0018] S3, feeding the raw material particles into a blow molding device, and obtaining an antibacterial PE film for packaging bags through a blow molding process.

[0019] Preferably, the thickness of the antibacterial PE film for packaging bags obtained in step S3 is 90-160 μm.

[0020] Preferably, the parameters of the twin-screw extruder are: the heating temperatures of zones 1-7 are as follows: 165-170°C, 175-180°C, 180-185°C, 180-185°C, 180-185°C, 170-175°C, 165-170°C, and the twin-screw speed is 30-45r / min.

[0021] Preferably, the blow molding ratio of the blow molding equipment is 2.6 to 2.9.

[0022] The present invention provides an antibacterial PE film for packaging bags and a preparation method thereof. The film has the following beneficial effects:

[0023] 1. The present invention improves the components of the antibacterial PE film, adds a predetermined amount of hydroxybenzoic acid ester and nano-silver composite antibacterial agent with antibacterial effect, the hydroxybenzoic acid ester can be evenly distributed in the PE film, and has an antibacterial effect. The nano-silver composite antibacterial agent is pre-bonded in maleic anhydride grafted polyethylene, and then mixed with linear low-density polyethylene, a plasticizer, and a coupling agent, extruded granulated, and blown into a film. The nano-silver composite antibacterial agent and the maleic anhydride grafted polyethylene are pre-mixed to obtain a high-viscosity intermediate with a high nano content and obvious antibacterial effect. In the subsequent mixing process, the nano-silver composite antibacterial agent in the high-viscosity intermediate has high stability and outstanding antibacterial effect. In addition, the introduction of maleic anhydride grafted polyethylene also significantly improves the mechanical strength of the antibacterial PE film.

[0024] 2. The present invention uses a high-concentration tea polyphenol solution mixed with nano-silver particles, and then prepares a nano-silver composite antibacterial agent containing tea polyphenols on the surface through evaporation, grinding, and screening processes. The nano-silver composite antibacterial agent has a more stable antibacterial effect and is more stable when mixed with maleic anhydride grafted polyethylene. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely below. 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.

[0026] Embodiment 1:

[0027] The embodiment of the present invention provides an antibacterial PE film for packaging bags, the main components of which are, by weight: 70-80 parts of linear low-density polyethylene, 1-1.2 parts of parabens, 2-8 parts of nano-silver composite antibacterial agent, 2-5 parts of maleic anhydride grafted polyethylene, 1-3 parts of plasticizer, and 1-3 parts of coupling agent.

[0028] Parabens have antibacterial and antifungal properties. They play their role as preservatives by destroying the cell membrane of microorganisms, denaturing the proteins in the cells, and inhibiting the activity of the respiratory enzymes and electron transfer enzymes in microbial cells. Parabens are weakly toxic and there are strict requirements on the content used. Nanosilver is a nanomaterial with unique physical and chemical properties. Its main characteristics include extremely small particle size, high specific surface area, good conductivity and strong antibacterial properties.

[0029] In this embodiment, the preparation method of maleic anhydride grafted polyethylene is: the temperature of the twin-screw extruder is set at 140°C-220°C, and the maleic anhydride is melt-grafted into high-density polyethylene using a twin-screw extruder to obtain maleic anhydride grafted polyethylene, and the amount of maleic anhydride used by weight is 20%-35%. The maleic anhydride in the maleic anhydride grafted polyethylene is relatively high, and the maleic anhydride grafted polyethylene formed thereby has a high grafting rate, poor fluidity, and a relatively high viscosity as a whole.

[0030] In this embodiment, the preparation method of the nano-silver composite antibacterial agent is as follows: step 1, preparing a tea polyphenol solution with a concentration of 15-25g / ml, and then adding nano-silver particles to the tea polyphenol solution at a ratio of 15-45g / ml, and stirring to obtain a solid-liquid mixture; step 2, pouring the solid-liquid mixture into a crucible for evaporation until the solid-liquid mixture is completely evaporated, grinding and sieving the obtained solid material to obtain the nano-silver composite antibacterial agent, and the tea polyphenols are attached to the surface of the nano-silver particles.

[0031] Specifically, a tea polyphenol solution with a concentration of 19 g / ml can be selected, and nano-silver particles can be added to the tea polyphenol solution at a ratio of 30 g / ml.

[0032] In this embodiment, the weight ratio of tea polyphenols to nano silver particles in the nano silver composite antibacterial agent is 1:1-3, preferably 1:1.5.

[0033] In this embodiment, the plasticizer is one or more of dioctyl phthalate, dibutyl phthalate, tricresyl phosphate, and triphenyl phosphate.

[0034] In this embodiment, the coupling agent is one or more of γ-aminopropyltriethoxysilane and isopropyl triisostearate titanate.

[0035] Embodiment 2:

[0036] A method for preparing an antibacterial PE film for packaging bags, comprising the following steps:

[0037] S1. Premix the nano-silver composite antibacterial agent and maleic anhydride grafted polyethylene in a mixing tank at 220° C.-260° C. to obtain a high-viscosity intermediate, preferably in a mixing tank at 245° C.

[0038] S2. Preliminarily mix the high-viscosity intermediate, linear low-density polyethylene, paraben, plasticizer and coupling agent at a temperature of 160° C.-210° C., and then send them into a twin-screw extruder for extrusion granulation to obtain raw material particles.

[0039] S3, feeding the raw material particles into a blow molding device, and obtaining an antibacterial PE film for packaging bags through a blow molding process.

[0040] In this embodiment, the thickness of the antibacterial PE film for packaging bags obtained in step S3 is 90-160 μm.

[0041] In this embodiment, the parameters of the twin-screw extruder are as follows: the heating temperatures of zones 1-7 are as follows: 165-170°C, 175-180°C, 180-185°C, 180-185°C, 180-185°C, 170-175°C, 165-170°C, and the twin-screw speed is 30-45r / min.

[0042] In this embodiment, the blow ratio of the blow molding equipment is 2.6 to 2.9.

[0043] Embodiment three:

[0044] The difference from Example 1 is that an antibacterial PE film for packaging bags mainly comprises, by weight, 70 parts of linear low-density polyethylene, 1 part of paraben, 2 parts of nano-silver composite antibacterial agent, 2 parts of maleic anhydride grafted polyethylene, 2.7 parts of plasticizer, and 2.2 parts of coupling agent.

[0045] Embodiment 4:

[0046] The difference from Example 1 is that an antibacterial PE film for packaging bags mainly comprises, by weight, 75 parts of linear low-density polyethylene, 1 part of paraben, 4 parts of nano-silver composite antibacterial agent, 3 parts of maleic anhydride grafted polyethylene, 2.7 parts of plasticizer, and 2.2 parts of coupling agent.

[0047] Embodiment five:

[0048] The difference from Example 1 is that an antibacterial PE film for packaging bags mainly comprises, by weight, 79 parts of linear low-density polyethylene, 1.2 parts of paraben, 6 parts of nano-silver composite antibacterial agent, 3 parts of maleic anhydride grafted polyethylene, 2.7 parts of plasticizer, and 2.2 parts of coupling agent.

[0049] Comparative Example 1:

[0050] The difference from Example 1 is that an antibacterial PE film for packaging bags mainly comprises, by weight, 79 parts of linear low-density polyethylene, 1.2 parts of paraben, 12 parts of nano-silver composite antibacterial agent, 2.7 parts of plasticizer, and 2.2 parts of coupling agent.

[0051] Comparative Example 2:

[0052] The difference from Example 1 is that an antibacterial PE film for packaging bags mainly comprises, by weight, 79 parts of linear low-density polyethylene, 1.2 parts of p-hydroxybenzoate, 8 parts of maleic anhydride grafted polyethylene, 2.7 parts of plasticizer, and 2.2 parts of coupling agent.

[0053] The antibacterial test method was carried out according to GB / T 31402-2023 Determination of the antibacterial activity on the surface of plastics and other non-porous materials. The antibacterial PE film for packaging bags prepared by the method in Example 2 according to the components and proportions in Example 3, Example 4, Example 5, Comparative Example 1 and Comparative Example 2 was subjected to an antibacterial test, and the antibacterial activity values ​​were as shown in Table 1 below (Comparative Example 1 and Comparative Example 2 omitted step S1 in Example 2, and the nanosilver composite antibacterial agent or maleic anhydride grafted polyethylene was directly preliminarily mixed with the remaining components).

[0054] The mechanical strength test method is to test the tensile properties of plastics in accordance with GB / T 1040.3-2006 / I S0527-3:1995. The antibacterial PE film for packaging bags prepared according to the method in Example 2 in the components and proportions in Example 3, Example 4, Example 5, Comparative Example 1 and Comparative Example 2 was subjected to a mechanical strength test, and the tensile strength and elongation at break were obtained as shown in Table 1 below.

[0055]

[0056]

[0057] Table 1

[0058] From the data analysis in the above table, it can be seen that by comparing Example 3 to Example 5 with Comparative Example 1 and Comparative Example 2, it can be seen that the antibacterial PE film for packaging bags prepared by adding nano-silver composite antibacterial agent and maleic anhydride grafted polyethylene at the same time has a more obvious antibacterial effect, and the nano-silver composite antibacterial agent and maleic anhydride grafted polyethylene are added at the same time, and the preparation method retains the process of pre-mixing the nano-silver composite antibacterial agent and the maleic anhydride grafted polyethylene in a mixing tank at 245°C to obtain a high-viscosity intermediate, and then pre-mixing the high-viscosity intermediate with the remaining ingredients. The tensile strength and elongation at break of the antibacterial PE film for packaging bags have obvious advantages, especially the addition of maleic anhydride grafted polyethylene, which has a higher gain in improving the elongation at break.

[0059] From the data analysis in the above table, it can be seen that by comparing Example 4 and Example 5 with Example 3, with the increase of the added amount of the nano-silver composite antibacterial agent and the maleic anhydride grafted polyethylene, the antibacterial effect of the prepared antibacterial PE film for packaging bags is significantly increased, but with the continued increase of the added amount of the nano-silver composite antibacterial agent and the maleic anhydride grafted polyethylene, the antibacterial effect of the antibacterial PE film for packaging bags is not significantly increased, so that the component ratio of the antibacterial PE film for packaging bags in Example 4 is the optimal component ratio.

[0060] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An antibacterial PE film for packaging bags, characterized in that: The main components are calculated by weight: 70-80 parts of linear low-density polyethylene, 1-1.2 parts of p-hydroxybenzoate, 2-8 parts of nano-silver composite antibacterial agent, 2-5 parts of maleic anhydride grafted polyethylene, 1-3 parts of plasticizer, and 1-3 parts of coupling agent.

2. The antibacterial PE film for packaging bags according to claim 1, characterized in that: The preparation method of the maleic anhydride grafted polyethylene is as follows: the temperature of the twin-screw extruder is set at 140° C. to 220° C., and maleic anhydride is melt-grafted onto high-density polyethylene using the twin-screw extruder to obtain the maleic anhydride grafted polyethylene; The amount of maleic anhydride used is 20%-35% by weight.

3. The antibacterial PE film for packaging bags according to claim 2, characterized in that: The preparation method of the nano silver composite antibacterial agent is: Step 1: preparing a tea polyphenol solution with a concentration of 15-25 g / ml, then adding nano silver particles to the tea polyphenol solution at a ratio of 15-45 g / ml, and stirring to obtain a solid-liquid mixture; Step 2: pour the solid-liquid mixture into a crucible for evaporation until the solid-liquid mixture is completely evaporated to dryness, and grind and sieve the obtained solid matter to obtain a nano-silver composite antibacterial agent.

4. The antibacterial PE film for packaging bags according to claim 3, characterized in that: The weight ratio of tea polyphenols to nano silver particles in the nano silver composite antibacterial agent is 1:1-3.

5. The antibacterial PE film for packaging bags according to claim 1, characterized in that: The plasticizer is one or more of dioctyl phthalate, dibutyl phthalate, tricresyl phosphate and triphenyl phosphate.

6. The antibacterial PE film for packaging bags and the preparation method thereof according to claim 1, characterized in that: The coupling agent is one or more of γ-aminopropyltriethoxysilane and isopropyl triisostearate titanate.

7. A method for preparing an antibacterial PE film for packaging bags, characterized in that: According to the composition and weight proportion of the antibacterial PE film for packaging bags in claims 1-6, the antibacterial PE film for packaging bags is prepared, comprising the following steps: S1. Premixing the nano-silver composite antibacterial agent and maleic anhydride grafted polyethylene in a mixing tank at 220° C.-260° C. to obtain a highly viscous intermediate; S2, preliminarily mixing the high-viscosity intermediate, linear low-density polyethylene, paraben, plasticizer, and coupling agent at a temperature of 160° C.-210° C., and then feeding into a twin-screw extruder for extrusion granulation to obtain raw material particles; S3, feeding the raw material particles into a blow molding device, and obtaining an antibacterial PE film for packaging bags through a blow molding process.

8. The method for preparing an antibacterial PE film for packaging bags according to claim 7, characterized in that: The thickness of the antibacterial PE film for packaging bags obtained in step S3 is 90-160 μm.

9. The method for preparing an antibacterial PE film for packaging bags according to claim 7, characterized in that: The parameters of the twin-screw extruder are as follows: the heating temperatures of zones 1-7 are as follows: 165-170°C, 175-180°C, 180-185°C, 180-185°C, 180-185°C, 170-175°C, 165-170°C, and the twin-screw speed is 30-45r / min.

10. The method for preparing an antibacterial PE film for packaging bags according to claim 7, characterized in that: The blow molding ratio of the blow molding equipment is 2.6 to 2.9.

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