Environment-friendly antibacterial high-barrier retort pouch and preparation method thereof

Abstract

The invention discloses an environment-friendly antibacterial high-barrier retort pouch and a preparation method thereof, belongs to the technical field of packaging materials, and aims to solve the problem that the antibacterial property and barrier property of the retort pouch need to be further improved. The environment-friendly antibacterial high-barrier retort pouch is obtained by laminating, curing and cutting a PET (Polyethylene Terephthalate) film, a nylon film and a modified polypropylene film through an adhesive; the preparation method of the modified polypropylene film comprises the following steps: reacting 10-hydroxycapraldehyde with amino modified titanium dioxide to obtain modified titanium dioxide; reacting allyl succinic anhydride with the modified titanium dioxide to obtain allyl succinic anhydride grafted modified titanium dioxide; carrying out melt blending on the intermediate I, polyethylene and a compatilizer to obtain a melt, and carrying out extrusion, tape casting, trimming and rolling to obtain a modified polypropylene film; the environment-friendly antibacterial high-barrier retort pouch prepared by the preparation method disclosed by the invention not only has antibacterial property and barrier property, but also has good high-temperature resistance.

Description

Technical Field

[0001] The invention relates to the technical field of packaging materials, and in particular to an environmentally friendly antibacterial high-barrier retort bag and a preparation method thereof. Background Art

[0002] Retort packaging materials are composite plastic film bags that can be heated and can maintain their structure and function during high-temperature retort. They are suitable for foods that require high-temperature processing, including canned foods, frozen foods, and ready-to-eat foods. These packaging materials must have good heat resistance, retort resistance, mechanical strength, and food safety to ensure that they will not break, deform, or release harmful substances under high temperature conditions. Aluminum foil is usually used in combination with other materials in packaging to enhance the mechanical strength of the packaging. It is used for foods that require sealing, high temperature resistance, and long shelf life, such as vacuum packaging and canned foods. However, aluminum foil also has the disadvantages of being easy to tear, opaque, limited recyclability, high cost, and easy to rust, and is not environmentally friendly. Existing retort packaging films mainly include aluminum-plastic composite films and transparent retort composite films. Since aluminum-plastic composite films cannot be microwaved, their scope of application is limited. Therefore, people have an increasing demand for retort films.

[0003] Chinese patent CN113276512B discloses a recyclable retort bag and a recyclable retort polyester film thereof, wherein the recyclable retort polyester film comprises a heat-sealing layer and at least one polyester layer, wherein the heat-sealing layer is formed by isophthalic acid, neopentyl glycol, polybutylene terephthalate, 1,4-cyclohexanedimethanol and polyethylene terephthalate-1,4-cyclohexanedimethanol, and the recyclable retort bag is made of the recyclable retort polyester film. The recyclable retort polyester film prepared by the invention has good heat-sealing properties and high-temperature retort resistance, but does not have good antibacterial properties. Chinese patent CN102173143B discloses a retort-resistant composite film and a retort-resistant bag, wherein the present invention provides a retort-resistant composite film comprising: a first CPP layer, a PVDC layer and a second CPP layer connected in sequence by an adhesive, wherein the composite film obtained thereby maintains a synchronous shrinkage rate of each layer in the heating, stretching and shrinking state, thereby avoiding curling of the composite film after stretching, but the barrier performance of the retort-resistant bag prepared by the present invention needs to be further improved. In summary, the development of a retort bag with good antibacterial properties and high barrier properties has a wide market value and important practical significance. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an environmentally friendly antibacterial high-barrier cooking bag and a preparation method thereof, which solves the problem that the antibacterial and barrier properties of the cooking bag need to be further improved.

[0005] In order to achieve the above object, the present invention provides a method for preparing an environmentally friendly antibacterial high-barrier retort bag, comprising the following steps:

[0006] PET film, nylon film and modified polypropylene film are bonded by adhesive, cured, cut and bagged to obtain an environmentally friendly antibacterial high barrier retort bag;

[0007] Wherein, the preparation method of modified polypropylene film comprises the following steps:

[0008] Step (1) mixing nano titanium dioxide, anhydrous ethanol and an aminosilane coupling agent uniformly, heating and reacting, and after the reaction is completed, centrifuging and drying to obtain amino-modified nano titanium dioxide;

[0009] Step (2) adding 10-hydroxydecanal, amino-modified nano titanium dioxide and potassium hydroxide into anhydrous ethanol, stirring evenly, heating, reacting, filtering, washing and drying after the reaction is completed to obtain modified nano titanium dioxide;

[0010] Step (3) adding allyl succinic anhydride and modified nano titanium dioxide to N,N-dimethylformamide, stirring evenly, adding sodium hydroxide, heating, reacting, filtering, washing, and drying to obtain allyl succinic anhydride grafted modified nano titanium dioxide;

[0011] Step (4) in a nitrogen atmosphere, polypropylene, allyl succinic anhydride grafted modified nano titanium dioxide and BPO are mixed, heated and kept warm for a period of time, heated and stirred, deionized water is added and kept warm, the reaction is completed, filtered, extracted with ethyl acetate, and dried to obtain intermediate I;

[0012] The intermediate I, polyethylene and a compatibilizer are melt-blended to obtain a melt, which is then extruded, cast, trimmed and rolled to obtain a modified polypropylene film.

[0013] Preferably, in step (1), the aminosilane coupling agent includes any one of γ-aminoethylaminopropyltrimethoxysilane and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane.

[0014] Preferably, in step (1), the mass ratio of nano-titanium dioxide, anhydrous ethanol and aminosilane coupling agent is (60-80):(2000-4000):(30-50); the reaction temperature is 65-75°C, and the reaction time is 6-8h.

[0015] Preferably, in step (2), the mass ratio of 10-hydroxydecanal, amino-modified nano-titanium dioxide, potassium hydroxide and anhydrous ethanol is (200-400):(80-100):(6-10):(1000-3000); the reaction temperature is 65-75°C, and the reaction time is 1.5-3.5h.

[0016] Preferably, in step (3), the mass ratio of allyl succinic anhydride, modified nano titanium dioxide, N,N-dimethylformamide and sodium hydroxide is (180-380):(200-280):(800-1600):(10-18); the reaction temperature is 60-80°C, and the reaction time is 6-10h.

[0017] Preferably, in step (4), the mass ratio of polypropylene, allyl succinic anhydride grafted modified nano-titanium dioxide, BPO, deionized water and ethyl acetate is (200-400):(10-20):(0.2-0.4):(50-80):(600-1400).

[0018] Preferably, in step (4), the first heating temperature is 55-65° C., and the insulation time is 1.5-3.5 h; the second heating temperature is 85-95° C., and the stirring time is 20-40 min.

[0019] Preferably, in step (4), the mass ratio of intermediate I, polyethylene and compatibilizer is (100-140):(20-40):(0.6-1).

[0020] Preferably, in step (4), the temperature of melt blending is 170-180°C.

[0021] Preferably, the compatibilizer is any one of polyoxyethylene monolaurate and polyoxyethylene lauryl ether.

[0022] Preferably, the die temperature of the extruder is 175-185°C.

[0023] Preferably, the melt blending time is 10-18 min, and the stirring speed during the blending process is 20-40 r / min.

[0024] Preferably, the melt blending is performed using a single screw extruder.

[0025] Preferably, the temperature of the casting roll is 75-85°C, the pulling speed of the casting roll is 7-8 m / min, and the temperature of the cooling roll is 25°C.

[0026] Preferably, the environmentally friendly antibacterial high barrier cooking bag is prepared by the method for preparing the environmentally friendly antibacterial high barrier cooking bag.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The nano titanium dioxide in the present invention is an inorganic particle, which has certain antibacterial and heat resistance. The addition of an appropriate amount can improve the heat resistance of the matrix; the nano titanium dioxide used in the present invention is small in size. After modification, it effectively avoids agglomeration, increases dispersibility, and maintains its functional stability. Aminosilane coupling agent is an organic silane, in which the silicon-oxygen bond energy is large, which can effectively improve thermal stability and increase the heat resistance of the matrix. Nano titanium dioxide can be used as a nucleating agent, and an appropriate amount of addition can increase the adhesion with the polypropylene matrix. Combined with the heterogeneous nucleation effect of nano rigid particles, it is beneficial to increase the barrier properties of the film. The amino group in the amino-modified nano titanium dioxide reacts chemically with the aldehyde group in 10-hydroxydecanal to generate a new group carbon-nitrogen double bond (-C=N-), that is, Schiff base. Schiff base has an inhibitory effect on a variety of harmful bacteria and has good activity against Escherichia coli and Staphylococcus aureus. The generation of carbon-nitrogen double bond (-C=N-) further increases the heat resistance of the matrix material. The introduced 10-hydroxydecanal has a long-chain structure and can improve the toughness of the matrix material.

[0029] 2. In the present invention, the anhydride group in the introduced allyl succinic anhydride can react with the hydroxyl group in the modified nano titanium dioxide to obtain allyl succinic anhydride grafted modified nano titanium dioxide, further improving the dispersibility of the nano titanium dioxide in the matrix material. The double bond structure contained in the allyl succinic anhydride grafted modified nano titanium dioxide can undergo a grafting reaction on the polypropylene chain to form a covalent bond connection, so that the bond between the allyl succinic anhydride grafted modified nano titanium dioxide and the polypropylene is tighter and more stable. The introduction of this covalent bond not only enhances the thermal stability and mechanical properties of the modified polypropylene film, but also improves the barrier properties of water vapor and oxygen. The nitrogen atoms and oxygen atoms in the allyl succinic anhydride grafted modified nano titanium dioxide can form hydrogen bonds with hydrogen atoms. The formation of hydrogen bonds will reduce the free volume between the polymer chains, limit the permeation channels of small molecules, and thus improve the barrier properties.

[0030] 3. The polyethylene used in the present invention is low-density polyethylene, which not only has good impact resistance, low temperature resistance and high temperature resistance, but also has certain moisture resistance, and is often used in the field of food packaging. Nylon film has high transparency, high tensile strength, and good heat resistance. Polypropylene has the characteristics of low density, high temperature resistance and easy molding. The introduced PET film can withstand higher temperatures, usually in the range of 130°C to 180°C, and is not easy to deform or degrade during the cooking process. The physical and chemical properties are relatively stable and can maintain its mechanical strength. The environmentally friendly antibacterial high-barrier cooking bag prepared by the present invention has a three-layer structure, which makes it have higher oxygen barrier and water vapor barrier properties. It is a safe, effective and highly sustainable packaging material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figure is a flow chart of the preparation of the environmentally friendly antibacterial high barrier retort bag of the present invention;

[0032] Figure 2 is a flow chart of the preparation of the modified polypropylene film of the present invention;

[0033] Figure 3 It is a schematic diagram of the reaction for preparing modified nano titanium dioxide in the present invention;

[0034] Figure 4 The schematic diagram of the reaction for preparing allyl succinic anhydride grafted modified nano titanium dioxide in the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than 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.

[0036] Example 1

[0037] This embodiment provides a method for preparing an environmentally friendly antibacterial high-barrier retort bag, comprising the following steps:

[0038] PET film, nylon film and modified polypropylene film are bonded by adhesive, cured, cut and bagged to obtain an environmentally friendly antibacterial high barrier retort bag with a film thickness of 80 μm;

[0039] Wherein, the preparation method of modified polypropylene film comprises the following steps:

[0040] Step (1) mixing nano titanium dioxide, anhydrous ethanol and γ-aminoethylaminopropyltrimethoxysilane in a mass ratio of 60:2000:30, reacting at 65° C. for 8 h, centrifuging after the reaction, and drying at 80° C. for 6 h to obtain amino-modified nano titanium dioxide;

[0041] Step (2) 10-hydroxydecanal, amino-modified nano titanium dioxide, potassium hydroxide and anhydrous ethanol are mixed in a mass ratio of 200:80:6:1000, reacted at 65° C. for 3.5 hours, filtered, washed with deionized water, and dried at 70° C. for 7 hours to obtain modified nano titanium dioxide;

[0042] Step (3) allyl succinic anhydride, modified nano titanium dioxide, N,N-dimethylformamide and sodium hydroxide are mixed in a mass ratio of 180:200:800:10, stirred, reacted at 60° C. for 10 h, filtered, washed with deionized water, and dried at 80° C. for 5 h to obtain allyl succinic anhydride grafted modified nano titanium dioxide;

[0043] Step (4) In a nitrogen atmosphere, polypropylene, allyl succinic anhydride grafted modified nano titanium dioxide and BPO are mixed, stirred at a speed of 100 r / min for 12 min, kept warm at 55° C. for 3.5 h, heated to 85° C., stirred at 80 r / min for 40 min, deionized water is added, and kept warm at 85° C. for 5 h. After the reaction is completed, the mixture is filtered, extracted with ethyl acetate, and dried at 90° C. for 100 min to obtain intermediate I;

[0044] The intermediate I, polyethylene and polyoxyethylene monolaurate are melt-blended in a single screw extruder at 170° C. and 20 r / min for 18 min to obtain a melt, the melt is extruded through a die head and cast onto a casting roll, and then cooled and formed by a cooling roll, and the edges are trimmed and rolled to obtain a modified polypropylene film;

[0045] Among them, the temperature of the die head is 175°C, the temperature of the casting roll is 75°C, the traction speed of the casting roll is 7m / min, and the temperature of the cooling roll is 25°C;

[0046] The mass ratio of polypropylene, allyl succinic anhydride grafted modified nano-titanium dioxide, BPO, deionized water and ethyl acetate is 200:10:0.2:50:600;

[0047] Wherein, the mass ratio of intermediate I, polyethylene and polyoxyethylene monolaurate is 100:20:0.6.

[0048] Example 2

[0049] This embodiment provides a method for preparing an environmentally friendly antibacterial high-barrier retort bag, comprising the following steps:

[0050] PET film, nylon film and modified polypropylene film are bonded by adhesive, cured, cut and bagged to obtain an environmentally friendly antibacterial high barrier retort bag with a film thickness of 80 μm;

[0051] Wherein, the preparation method of modified polypropylene film comprises the following steps:

[0052] Step (1) mixing nano titanium dioxide, anhydrous ethanol and γ-aminoethylaminopropyltrimethoxysilane in a mass ratio of 65:2500:35, reacting at 67° C. for 7.5 h, centrifuging after the reaction, and drying at 85° C. for 5.5 h to obtain amino-modified nano titanium dioxide;

[0053] Step (2) 10-hydroxydecanal, amino-modified nano titanium dioxide, potassium hydroxide and anhydrous ethanol are mixed in a mass ratio of 250:85:7:1500, reacted at 67° C. for 3 h, filtered, washed with deionized water, and dried at 75° C. for 6.5 h to obtain modified nano titanium dioxide;

[0054] Step (3) allyl succinic anhydride, modified nano titanium dioxide, N,N-dimethylformamide and sodium hydroxide are mixed in a mass ratio of 230:220:1000:12, stirred, reacted at 65°C for 9 hours, filtered, washed with deionized water, and dried at 85°C for 4.5 hours to obtain allyl succinic anhydride grafted modified nano titanium dioxide;

[0055] Step (4) In a nitrogen atmosphere, polypropylene, allyl succinic anhydride grafted modified nano titanium dioxide and BPO are mixed, stirred at a speed of 105 r / min for 11 min, kept warm at 57° C. for 3 h, heated to 87° C., stirred at 85 r / min for 35 min, deionized water is added, and kept warm at 87° C. for 4.5 h. After the reaction is completed, the mixture is filtered, extracted with ethyl acetate, and dried at 92° C. for 90 min to obtain intermediate I;

[0056] The intermediate I, polyethylene and polyoxyethylene monolaurate are melt-blended in a single screw extruder at 172° C. and a rotation speed of 25 r / min for 16 min to obtain a melt, and the melt is extruded through a die head and cast onto a casting roll, and then cooled and formed by a cooling roll, and the edges are trimmed and rolled to obtain a modified polypropylene film;

[0057] Among them, the temperature of the die head is 177°C, the temperature of the casting roll is 77°C, the pulling speed of the casting roll is 7m / min, and the temperature of the cooling roll is 25°C;

[0058] The mass ratio of polypropylene, allyl succinic anhydride grafted modified nano-titanium dioxide, BPO, deionized water and ethyl acetate is 250:12:0.25:57:800;

[0059] Among them, the mass ratio of intermediate I, polyethylene and polyoxyethylene monolaurate is 110:25:0.7.

[0060] Example 3

[0061] This embodiment provides a method for preparing an environmentally friendly antibacterial high-barrier retort bag, comprising the following steps:

[0062] PET film, nylon film and modified polypropylene film are bonded by adhesive, cured, cut and bagged to obtain an environmentally friendly antibacterial high barrier retort bag with a film thickness of 80 μm;

[0063] Wherein, the preparation method of modified polypropylene film comprises the following steps:

[0064] Step (1) mixing nano titanium dioxide, anhydrous ethanol and γ-aminoethylaminopropyltrimethoxysilane in a mass ratio of 70:3000:40, reacting at 70° C. for 7 hours, centrifuging after the reaction, and drying at 90° C. for 5 hours to obtain amino-modified nano titanium dioxide;

[0065] Step (2) 10-hydroxydecanal, amino-modified nano titanium dioxide, potassium hydroxide and anhydrous ethanol are mixed in a mass ratio of 300:90:8:2000, reacted at 70° C. for 2.5 h, filtered, washed with deionized water, and dried at 80° C. for 6 h to obtain modified nano titanium dioxide;

[0066] Step (3) allyl succinic anhydride, modified nano titanium dioxide, N,N-dimethylformamide and sodium hydroxide are mixed in a mass ratio of 280:240:1200:14, stirred, reacted at 70°C for 8h, filtered, washed with deionized water, and dried at 90°C for 4h to obtain allyl succinic anhydride grafted modified nano titanium dioxide;

[0067] Step (4) In a nitrogen atmosphere, polypropylene, allyl succinic anhydride grafted modified nano titanium dioxide and BPO are mixed, stirred at a speed of 110 r / min for 10 min, kept warm at 60° C. for 2.5 h, heated to 90° C., stirred at 90 r / min for 30 min, deionized water is added, and kept warm at 90° C. for 4 h. After the reaction is completed, the mixture is filtered, extracted with ethyl acetate, and dried at 95° C. for 80 min to obtain intermediate I;

[0068] The intermediate I, polyethylene and polyoxyethylene monolaurate are melt-blended in a single screw extruder at 175° C. and a rotation speed of 30 r / min for 14 min to obtain a melt, the melt is extruded through a die head and cast onto a casting roll, and then cooled and formed by a cooling roll, and the edges are trimmed and rolled to obtain a modified polypropylene film;

[0069] Among them, the temperature of the die head is 180°C, the temperature of the casting roll is 80°C, the traction speed of the casting roll is 7.5m / min, and the temperature of the cooling roll is 25°C;

[0070] The mass ratio of polypropylene, allyl succinic anhydride grafted modified nano-titanium dioxide, BPO, deionized water and ethyl acetate is 300:15:0.3:65:1000;

[0071] Among them, the mass ratio of intermediate I, polyethylene and polyoxyethylene monolaurate is 120:30:0.8.

[0072] Example 4

[0073] This embodiment provides a method for preparing an environmentally friendly antibacterial high-barrier retort bag, comprising the following steps:

[0074] PET film, nylon film and modified polypropylene film are bonded by adhesive, cured, cut and bagged to obtain an environmentally friendly antibacterial high barrier retort bag with a film thickness of 80 μm;

[0075] Wherein, the preparation method of modified polypropylene film comprises the following steps:

[0076] Step (1) mixing nano titanium dioxide, anhydrous ethanol and γ-aminoethylaminopropyltrimethoxysilane in a mass ratio of 75:3500:45, reacting at 72° C. for 6.5 h, centrifuging after the reaction, and drying at 95° C. for 4.5 h to obtain amino-modified nano titanium dioxide;

[0077] Step (2) 10-hydroxydecanal, amino-modified nano titanium dioxide, potassium hydroxide and anhydrous ethanol are mixed in a mass ratio of 350:95:9:2500, reacted at 72° C. for 2 h, filtered, washed with deionized water, and dried at 85° C. for 5.5 h to obtain modified nano titanium dioxide;

[0078] Step (3) allyl succinic anhydride, modified nano titanium dioxide, N,N-dimethylformamide and sodium hydroxide are mixed in a mass ratio of 330:260:1400:16, stirred, reacted at 75°C for 7h, filtered, washed with deionized water, and dried at 95°C for 3.5h to obtain allyl succinic anhydride grafted modified nano titanium dioxide;

[0079] Step (4) In a nitrogen atmosphere, polypropylene, allyl succinic anhydride grafted modified nano titanium dioxide and BPO are mixed, stirred at a speed of 115 r / min for 9 minutes, kept warm at 62° C. for 2 hours, heated to 92° C., stirred at 95 r / min for 25 minutes, deionized water is added, and kept warm at 92° C. for 3.5 hours. After the reaction is completed, the mixture is filtered, extracted with ethyl acetate, and dried at 97° C. for 70 minutes to obtain intermediate I;

[0080] The intermediate I, polyethylene and polyoxyethylene monolaurate are melt-blended in a single screw extruder at 177° C. and 35 r / min for 12 min to obtain a melt, the melt is extruded through a die head and cast onto a casting roll, and then cooled and formed by a cooling roll, and the edges are trimmed and rolled to obtain a modified polypropylene film;

[0081] Among them, the temperature of the die head is 182°C, the temperature of the casting roll is 82°C, the pulling speed of the casting roll is 8m / min, and the temperature of the cooling roll is 25°C;

[0082] Among them, the mass ratio of polypropylene, allyl succinic anhydride grafted modified nano titanium dioxide, BPO, deionized water and ethyl acetate is 350:17:0.35:72:1200;

[0083] Among them, the mass ratio of intermediate I, polyethylene and polyoxyethylene monolaurate is 130:35:0.9.

[0084] Example 5

[0085] This embodiment provides a method for preparing an environmentally friendly antibacterial high-barrier retort bag, comprising the following steps:

[0086] PET film, nylon film and modified polypropylene film are bonded by adhesive, cured, cut and bagged to obtain an environmentally friendly antibacterial high barrier retort bag with a film thickness of 80 μm;

[0087] Wherein, the preparation method of modified polypropylene film comprises the following steps:

[0088] Step (1) mixing nano titanium dioxide, anhydrous ethanol and γ-aminoethylaminopropyltrimethoxysilane in a mass ratio of 80:4000:50, reacting at 75° C. for 8 hours, centrifuging after the reaction, and drying at 100° C. for 4 hours to obtain amino-modified nano titanium dioxide;

[0089] Step (2) 10-hydroxydecanal, amino-modified nano titanium dioxide, potassium hydroxide and anhydrous ethanol are mixed in a mass ratio of 400:100:10:3000, reacted at 75° C. for 1.5 h, filtered, washed with deionized water, and dried at 90° C. for 5 h to obtain modified nano titanium dioxide;

[0090] Step (3) allyl succinic anhydride, modified nano titanium dioxide, N,N-dimethylformamide and sodium hydroxide are mixed in a mass ratio of 380:280:1600:18, stirred, reacted at 80°C for 6 hours, filtered, washed with deionized water, and dried at 100°C for 3 hours to obtain allyl succinic anhydride grafted modified nano titanium dioxide;

[0091] Step (4) In a nitrogen atmosphere, polypropylene, allyl succinic anhydride grafted modified nano titanium dioxide and BPO are mixed, stirred at a speed of 120 r / min for 8 min, kept warm at 65° C. for 1.5 h, heated to 95° C., stirred at 100 r / min for 20 min, deionized water is added, and kept warm at 95° C. for 3 h. After the reaction is completed, the mixture is filtered, extracted with ethyl acetate, and dried at 100° C. for 60 min to obtain intermediate I;

[0092] The intermediate I, polyethylene and polyoxyethylene monolaurate are melt-blended in a single screw extruder at 180° C. and 40 r / min for 10 min to obtain a melt, the melt is extruded through a die head and cast onto a casting roll, and then cooled and formed by a cooling roll, and the edges are trimmed and rolled to obtain a modified polypropylene film;

[0093] Among them, the temperature of the die head is 185°C, the temperature of the casting roll is 85°C, the pulling speed of the casting roll is 8m / min, and the temperature of the cooling roll is 25°C;

[0094] Among them, the mass ratio of polypropylene, allyl succinic anhydride grafted modified nano titanium dioxide, BPO, deionized water and ethyl acetate is 400:20:0.4:80:1400;

[0095] Wherein, the mass ratio of intermediate I, polyethylene and polyoxyethylene monolaurate is 140:40:1.

[0096] Comparative Example 1

[0097] This comparative example provides a method for preparing an environmentally friendly antibacterial high-barrier retort bag, comprising the following steps:

[0098] PET film, nylon film and modified polypropylene film are bonded by adhesive, cured, cut and bagged to obtain an environmentally friendly antibacterial high barrier retort bag with a film thickness of 80 μm;

[0099] Wherein, the preparation method of modified polypropylene film comprises the following steps:

[0100] Step (1) mixing nano titanium dioxide, anhydrous ethanol and γ-aminoethylaminopropyltrimethoxysilane in a mass ratio of 60:2000:30, reacting at 65° C. for 8 h, centrifuging after the reaction, and drying at 80° C. for 6 h to obtain amino-modified nano titanium dioxide;

[0101] Step (2) 10-hydroxydecanal, amino-modified nano titanium dioxide, potassium hydroxide and anhydrous ethanol are mixed in a mass ratio of 200:80:6:1000, reacted at 65° C. for 3.5 hours, filtered, washed with deionized water, and dried at 70° C. for 7 hours to obtain modified nano titanium dioxide;

[0102] Step (3) melt-blending polypropylene, modified nano-titanium dioxide, polyethylene and polyoxyethylene monolaurate in a single screw extruder at 170° C. and a rotation speed of 20 r / min for 18 min to obtain a melt, extruding the melt through a die head and casting it onto a casting roll, then cooling and forming it through a cooling roll, trimming and rolling it, and obtaining a modified polypropylene film;

[0103] Among them, the temperature of the die head is 175°C, the temperature of the casting roll is 75°C, the pulling speed of the casting roll is 7m / min, and the temperature of the cooling roll is 25°C;

[0104] Among them, the mass ratio of polypropylene, modified nano titanium dioxide, polyethylene and polyoxyethylene monolaurate is 95.5:4.5:20:0.6.

[0105] Comparative Example 2

[0106] This comparative example provides a method for preparing an environmentally friendly antibacterial high-barrier retort bag, comprising the following steps:

[0107] PET film, nylon film and modified polypropylene film are bonded by adhesive, cured, cut and bagged to obtain an environmentally friendly antibacterial high barrier retort bag with a film thickness of 80 μm;

[0108] Wherein, the preparation method of modified polypropylene film comprises the following steps:

[0109] Step (1) mixing nano titanium dioxide, anhydrous ethanol and γ-aminoethylaminopropyltrimethoxysilane in a mass ratio of 60:2000:30, reacting at 65° C. for 8 h, centrifuging after the reaction, and drying at 80° C. for 6 h to obtain amino-modified nano titanium dioxide;

[0110] Step (2) polypropylene, amino-modified nano titanium dioxide, polyethylene and polyoxyethylene monolaurate are melt-blended in a single screw extruder at 170° C. and a rotation speed of 20 r / min for 18 min to obtain a melt, the melt is extruded through a die head and cast onto a casting roll, and then cooled and formed by a cooling roll, trimmed and rolled to obtain a modified polypropylene film;

[0111] Among them, the temperature of the die head is 175°C, the temperature of the casting roll is 75°C, the traction speed of the casting roll is 7m / min, and the temperature of the cooling roll is 25°C;

[0112] Among them, the mass ratio of polypropylene, amino-modified nano titanium dioxide, polyethylene and polyoxyethylene monolaurate is 95.5:4.5:20:0.6.

[0113] In the embodiments and comparative examples of the present invention, polyethylene is a linear low-density polyethylene from Zhenhai Refining and Chemical, brand: DNDA-8320; polypropylene is purchased from PetroChina Daqing Petrochemical Company, model: T30S; PET film is from Shanghai Fuzhong Industrial Co., Ltd.; nylon film is from Dongguan Ruicheng Plastic Products Factory; nano titanium dioxide is from Xuancheng Jingrui New Materials Co., Ltd., model: JR05, with an average particle size of 5nm; 10-hydroxydecanal is from Jiangsu Aikang Biomedicine Research and Development Co., Ltd., CAS number: 22136-92-1, with a purity of 95%; allyl succinic anhydride is from Shanghai MacLean Biochemical Technology Co., Ltd., CAS number: 7539-12-0; and the adhesive is a two-component solvent-free cooking-resistant adhesive 7735 produced by Henkel of Germany.

[0114] Corresponding tests were performed on the modified polypropylene films prepared in Examples 1-5 and Comparative Examples 1-2, wherein the film thickness was 50 μm. The specific test results are as follows:

[0115] (1) Tensile test: The test method refers to the standard GB13022-91 "Test method for tensile properties of plastic films", the tensile speed is 250±25mm / min, and the test results are shown in Table 1:

[0116] Table 1

[0117]

[0118] As shown in Table 1, the modified polypropylene film prepared by the present invention has high tensile strength, especially the tensile performance of Example 1 is the best, reaching 28.5MPa. Compared with Example 1, Comparative Example 1 lacks the introduction of allyl succinic anhydride, which reduces the compatibility between the modified nano titanium dioxide and polypropylene and polyethylene, and the dispersibility is lower than that of Example 1, so the tensile performance of the modified polypropylene film prepared by Comparative Example 1 is lower than that of Example 1; Comparative Example 2 lacks the long-chain structure of 10-hydroxydecanal, and the toughness performance of the matrix is ​​lower than that of Comparative Example 1, so the tensile performance in Comparative Example 1 is better than that of Comparative Example 2.

[0119] (2) Barrier performance test: Water vapor transmission rate test: According to GB / T26253-2010 "Determination of water vapor transmission rate of plastic film and sheeting by infrared detector method", the test was carried out using a BASIC301 water vapor transmission rate tester at a temperature of 23°C and a relative humidity of 85%; Oxygen transmission rate test: The test was carried out using a VACV1 oxygen transmission rate tester at a temperature of 23°C and a relative humidity of 0%. The specific test results are shown in Table 2;

[0120] Table 2

[0121]

[0122] It can be seen from the test results in Table 2 that the modified polypropylene films prepared in Examples 1-5 have good barrier properties. Among them, polyethylene itself has good water vapor barrier properties. After adding the compatibilizer polyoxyethylene monolaurate, the compatibility with other materials is increased, which is beneficial to the barrier properties. Nano-titanium dioxide can be used as a nucleating agent. It is added in an appropriate amount to increase the adhesion with the polypropylene matrix. Combined with the heterogeneous nucleation effect of nano-rigid particles, it is beneficial to increase the barrier properties of the film. The dispersion performance of the allyl succinic anhydride grafted modified nano-titanium dioxide obtained after the modification treatment is better than that of amino-modified nano-titanium dioxide and modified nano-titanium dioxide. In Example 1, the introduction of allyl succinic anhydride grafted modified nano titanium dioxide into polypropylene gives the modified polypropylene film excellent barrier properties and antibacterial properties. Once it is missing, its barrier properties naturally decrease, so the barrier performance of Comparative Example 1 is lower than that of Example 1; in Comparative Example 2, 10-hydroxydecanal is missing, and the oxygen atoms contained in it can form hydrogen bonds with hydrogen atoms. The hydrogen bonds will reduce the diffusion behavior of molecules in the polymer and increase the difficulty of small molecules passing through the film, thereby reducing the air permeability of the film and improving the barrier properties. Once it is missing, the number of hydrogen bonds formed is reduced, so the barrier performance is reduced, that is, the barrier performance of Comparative Example 1 is better than that of Comparative Example 2.

[0123] (3) Antibacterial performance test: The test method refers to the standard QB / T2591-2003 "Antibacterial plastic antibacterial performance test method and antibacterial effect", and the test results are shown in Table 3:

[0124] Table 3

[0125]

[0126] As shown in Table 3, the modified polypropylene film prepared by the present invention has a good antibacterial effect. Compared with Example 1, since allyl succinic anhydride is not added, the dispersibility of nano titanium dioxide is reduced, and its antibacterial performance is reduced; in Comparative Example 1, the aldehyde group in 10-hydroxydecanal reacts with the amino group in the amino-modified nano titanium dioxide to form a Schiff base with antibacterial properties, further enhancing the antibacterial performance. Once 10-hydroxydecanal is lacking, the Schiff base cannot be formed, so the antibacterial performance of the modified polypropylene film in Comparative Example 2 is lower than that in Comparative Example 1.

[0127] Although the embodiments of the present invention have been shown and described, it will be understood 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 all equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing an environmentally friendly antibacterial high barrier retort bag, characterized in that: The following steps are involved: PET film, nylon film and modified polypropylene film are bonded by adhesive, cured, cut and bagged to obtain an environmentally friendly antibacterial high barrier retort bag; Wherein, the preparation method of modified polypropylene film comprises the following steps: Step (1) uniformly mixing titanium dioxide, anhydrous ethanol and an aminosilane coupling agent, heating and reacting, and after the reaction is completed, centrifuging and drying to obtain amino-modified titanium dioxide; Step (2) adding 10-hydroxydecanal, amino-modified titanium dioxide and potassium hydroxide to anhydrous ethanol, stirring evenly, heating, reacting, filtering, washing and drying after the reaction is completed to obtain modified titanium dioxide; Step (3) adding allyl succinic anhydride and modified titanium dioxide to N,N-dimethylformamide, stirring evenly, adding sodium hydroxide, heating, reacting, filtering, washing, and drying to obtain allyl succinic anhydride grafted modified titanium dioxide; Step (4) in a nitrogen atmosphere, polypropylene, allyl succinic anhydride grafted modified titanium dioxide and BPO are mixed, heated and kept warm for a period of time, heated and stirred, deionized water is added and kept warm, the reaction is completed, filtered, extracted with ethyl acetate, and dried to obtain intermediate I; The intermediate I, polyethylene and a compatibilizer are melt-blended to obtain a melt, which is then extruded, cast, trimmed and rolled to obtain a modified polypropylene film.

2. The method for preparing an environmentally friendly antibacterial high barrier retort bag according to claim 1, characterized in that: In step (1), the aminosilane coupling agent includes any one of γ-aminoethylaminopropyltrimethoxysilane and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane.

3. The method for preparing an environmentally friendly antibacterial high barrier retort bag according to claim 1, characterized in that: In step (1), the mass ratio of titanium dioxide, anhydrous ethanol and aminosilane coupling agent is (60-80):(2000-4000):(30-50); the reaction temperature is 65-75° C., and the reaction time is 6-8 hours.

4. The method for preparing an environmentally friendly antibacterial high barrier retort bag according to claim 1, characterized in that: In step (2), the mass ratio of 10-hydroxydecanal, amino-modified titanium dioxide, potassium hydroxide and anhydrous ethanol is (200-400):(80-100):(6-10):(1000-3000); the reaction temperature is 65-75° C., and the reaction time is 1.5-3.5 h.

5. The method for preparing an environmentally friendly antibacterial high barrier retort bag according to claim 1, characterized in that: In step (3), the mass ratio of allyl succinic anhydride, modified titanium dioxide, N,N-dimethylformamide and sodium hydroxide is (180-380):(200-280):(800-1600):(10-18); the reaction temperature is 60-80°C, and the reaction time is 6-10h.

6. The method for preparing an environmentally friendly antibacterial high barrier retort bag according to claim 1, characterized in that: In step (4), the mass ratio of polypropylene, allyl succinic anhydride grafted modified titanium dioxide, BPO, deionized water and ethyl acetate is (200-400):(10-20):(0.2-0.4):(50-80):(600-1400).

7. The method for preparing an environmentally friendly antibacterial high barrier retort bag according to claim 1, characterized in that: In step (4), the first heating temperature is 55-65° C., and the insulation time is 1.5-3.5 h; the second heating temperature is 85-95° C., and the stirring time is 20-40 min.

8. The method for preparing an environmentally friendly antibacterial high barrier retort bag according to claim 1, characterized in that: In step (4), the mass ratio of intermediate I, polyethylene and compatibilizer is (100-140):(20-40):(0.6-1).

9. The method for preparing an environmentally friendly antibacterial high barrier retort bag according to claim 1, characterized in that: In step (4), the temperature of melt blending is 170-180°C.

10. An environmentally friendly antibacterial high barrier cooking bag prepared by the method for preparing an environmentally friendly antibacterial high barrier cooking bag according to any one of claims 1 to 9.

Images