An environmentally friendly, biodegradable and highly barrier emulsion and its preparation method

Abstract

The present invention relates to the field of barrier emulsions, and provides an environmentally friendly, degradable and highly efficient barrier emulsion and a preparation method thereof. By weight, the barrier emulsion comprises the following raw materials: 40-60 parts of L-lactide, 10-20 parts of ε-caprolactone, 5-10 parts of modified montmorillonite, 1-3 parts of antibacterial agent, 0.2-1 part of initiator, 10-20 parts of solvent, 0.5-2 parts of emulsifier, and 200-300 parts of deionized water. The barrier emulsion provided by the present invention has the characteristics of environmental friendliness, degradability, high barrier property and high antibacterial property, and has good commercial application value.

Description

Technical Field

[0001] The present invention relates to the field of barrier emulsions, and particularly to an environmentally friendly, degradable, and highly efficient barrier emulsion and a preparation method thereof. Background Art

[0002] In the field of food packaging, barrier emulsions are special coating materials used to improve the barrier properties of food packaging materials. Their main function is to prevent small molecules such as oxygen, water vapor, and odors from passing through the packaging material, thereby extending the shelf life and freshness of food. With the gradual strengthening of people's awareness of the quality of life and safety and environmental protection, environmentally friendly and degradable barrier emulsions are becoming increasingly popular, and fluorine-containing barrier emulsions are gradually being phased out due to their non-environmental friendliness and non-degradability.

[0003] Polylactic acid has good application prospects in the field of food packaging due to its excellent biodegradability, biocompatibility, processability, good transparency, and gloss. Moreover, polylactic acid also has certain barrier properties and can effectively prevent the penetration of oxygen, moisture, etc. However, when using pure polylactic acid as a barrier emulsion, some barrier fillers such as montmorillonite need to be added. However, montmorillonite has problems such as easy agglomeration and poor dispersion in the polylactic acid matrix.

[0004] Patent CN 113789108A discloses a high-barrier antibacterial polycaprolactone emulsion, its preparation method and application, including components such as ε-caprolactone, L-lactide, antioxidant, and antibacterial agent, which has good barrier properties and degradability. However, this application selects graphene oxide as the antibacterial agent, and graphene oxide has problems with poor dispersion, resulting in its inability to play a good role and even leading to a decline in the comprehensive performance of the emulsion.

[0005] Therefore, there is an urgent need in the market for an environmentally friendly, degradable, highly barrier, and highly antibacterial environmentally friendly degradable and highly efficient barrier emulsion. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the present invention uses polylactic acid as the main component of the barrier emulsion, and adds modified montmorillonite, antibacterial agent, etc. to synthesize an environmentally friendly, degradable, highly efficient barrier emulsion, which has the characteristics of environmental friendliness, degradability, high barrier property, and high antibacterial property.

[0007] In order to achieve the above object, the technical solutions adopted by the present invention are as follows:

[0008] On the one hand, the present invention provides an environmentally friendly, degradable and highly barrier emulsion. By weight, the barrier emulsion comprises the following raw materials: 40-60 parts of L-lactide, 10-20 parts of ε-caprolactone, 5-10 parts of modified montmorillonite, 1-3 parts of antibacterial agent, 0.2-1 part of initiator, 10-20 parts of solvent, 0.5-2 parts of emulsifier, and 200-300 parts of deionized water.

[0009] Among them, the initiator is stannous octoate; the solvent is ethyl acetate.

[0010] In some embodiments of the present invention, the preparation method of the modified montmorillonite comprises the following steps:

[0011] (1) Add erucic acid and monoethanolamine 1 into a reaction vessel. Under an inert atmosphere, heat up to 160-170 °C, stir for 4-5 h, cool down to 50-70 °C, add monoethanolamine 2 and sodium methoxide, heat up to 90-110 °C, and stir for 3-4 h to obtain product 1 for standby;

[0012] (2) Mix product 1 from step (1) with tetrahydrofuran, ether, and acetonitrile, stir, add phosphorus oxychloride, triethylamine, ethylene glycol, and octadecyldimethyl tertiary amine, stir at -2 to 2 °C for 3-5 h, heat up to 60-70 °C and stir for 35-37 h, perform recrystallization, and dry to obtain product 2 for standby;

[0013] (3) Add montmorillonite into deionized water, stir, add product 2 from step (2) and nanocellulose, stir at 80-100 °C for 3-5 h, centrifuge, wash, and dry to obtain the modified montmorillonite.

[0014] In some embodiments of the present invention, in step (1), the mass ratio of erucic acid to monoethanolamine 1 is 1:(0.1-0.2).

[0015] Preferably, the mass ratio of erucic acid to monoethanolamine 1 is 1:0.14.

[0016] In some embodiments of the present invention, in step (2), the mass ratio of product 1, phosphorus oxychloride, and octadecyldimethyl tertiary amine is 1:(0.4-0.5):(0.7-0.8).

[0017] Preferably, in step (2), the mass ratio of product 1, phosphorus oxychloride, and octadecyldimethyl tertiary amine is 1:0.45:0.75.

[0018] In some embodiments of the present invention, in step (3), the mass ratio of montmorillonite, product 2, and nanocellulose is 1:(0.6-1):(0.8-1.2).

[0019] Preferably, in the step (3), the mass ratio of montmorillonite, product 2 and nanocellulose is 1:0.8:1.

[0020] Montmorillonite is a silicate mineral with a layered and microporous structure, which enables it to effectively block gases such as oxygen. Adding it to the barrier emulsion can significantly improve the oxygen barrier property of the barrier emulsion. However, since the natural montmorillonite layers are bonded by van der Waals forces with weak bond energy and contain many hydroxyl hydrophilic groups in the unit cell, showing strong hydrophilicity, its dispersibility in the polylactic acid organic phase is poor, severely limiting the exertion of its barrier performance.

[0021] On the one hand, the applicant uses erucic acid and monoethanolamine as raw materials to prepare product 1, then reacts product 1 with phosphorus oxychloride, triethylamine, ethylene glycol and octadecyl dimethyl tertiary amine to synthesize product 2, and further modifies montmorillonite with product 2. Product 2 contains multiple hydrophilic and hydrophobic groups, which can smoothly enter the interlayer of montmorillonite for intercalation modification, and make the modified montmorillonite more lipophilic, so that montmorillonite has a good dispersion effect in the barrier emulsion; on the other hand, the applicant introduces nanocellulose to mix-modify montmorillonite. Nanocellulose, as an environmentally friendly natural polymer material, has a dense and uniform network structure, and can thus provide good oxygen barrier performance, further enhancing the oxygen barrier performance of the modified montmorillonite.

[0022] In some embodiments of the present invention, the preparation method of the antibacterial agent comprises the following steps:

[0023] 1) Add chitosan to an aqueous hydrochloric acid solution, stir at 50 - 70 °C for 3 - 5 h, add an aqueous solution of dicyandiamide, stir, heat up to 90 - 100 °C, stir for 3 - 5 h, cool to room temperature, precipitate, centrifuge, add deionized water, dialyze, and freeze-dry to obtain chitosan biguanide for standby;

[0024] 2) Add nano-titanium dioxide to an aqueous ethanol solution, sonicate to obtain solution 1 for standby, add KH560 to an aqueous ethanol solution, sonicate to obtain solution 2 for standby, mix solution 1 and solution 2, stir at 70 - 90 °C for 7 - 9 h, centrifuge, wash, and dry to obtain pretreated titanium dioxide for standby;

[0025] 3) Add the chitosan biguanide from step 1) to deionized water, stir to obtain solution 3 for standby, add the pretreated titanium dioxide from step 2) to deionized water, sonicate, add solution 3 and tetramethylethylenediamine, stir at 45 - 55 °C for 5 - 7 h, centrifuge, wash, and dry to obtain the antibacterial agent.

[0026] Wherein, in the step 2), the mass ratio of nano-titanium dioxide and KH560 is 1:(0.8 - 1.2).

[0027] In some embodiments of the present invention, in step 1), the mass ratio of chitosan to dicyandiamide in the dicyandiamide aqueous solution is 1:(2 - 3).

[0028] Preferably, in step 1), the mass ratio of chitosan to dicyandiamide in the dicyandiamide aqueous solution is 1:2.5.

[0029] In some embodiments of the present invention, in step 3), the mass ratio of chitosan biguanide to pretreated titanium dioxide is 1:(0.4 - 0.6).

[0030] Preferably, in step 3), the mass ratio of chitosan biguanide to pretreated titanium dioxide is 1:0.5.

[0031] Chitosan is a natural biodegradable substance and has broad-spectrum antibacterial properties. However, the thermal stability of chitosan itself needs to be improved, and its water solubility is limited, which restricts its application in the field of food packaging; nano-titanium dioxide has the characteristics of broad-spectrum antibacterial, stable and persistent, safe and non-toxic, and has been widely used in the field of food packaging. However, it has the problems of easy agglomeration and poor dispersibility, resulting in the inability to meet the requirements of high antibacterial activity when used alone.

[0032] The applicant uses dicyandiamide to modify chitosan by guanidylation to obtain chitosan biguanide. Chitosan biguanide is an antibacterial agent with a cationic charge. While maintaining the biodegradability and antibacterial properties of chitosan itself, the introduction of the biguanide group can effectively improve the thermal stability, water solubility, biodegradability and antibacterial properties of chitosan; further, the applicant grafts chitosan biguanide on the surface of nano-titanium dioxide. First, the applicant modifies nano-titanium dioxide with the silane coupling agent KH560 to make epoxy groups appear on the surface of nano-titanium dioxide, and then undergoes a ring-opening reaction with the amino group of chitosan biguanide to successfully graft and obtain an antibacterial agent, which effectively solves the problem of poor dispersibility of nano-titanium dioxide on the one hand and improves the thermal stability and antibacterial properties of chitosan on the other hand.

[0033] In some embodiments of the present invention, the emulsifier is Tween 40 or Tween 60.

[0034] On the other hand, the present invention also provides a method for preparing the environmentally friendly biodegradable and highly barrier emulsion described in the above technical solution, including the following steps:

[0035] S1. Add L-lactide to a solvent, heat to 50 - 60 °C, stir and mix with ε-caprolactone, stir, add an emulsifier and an initiator, stir, add deionized water, and stir to obtain an intermediate product for standby;

[0036] S2. Introduce an inert gas into the intermediate product of step S1, heat it to 60 - 70 °C, stir, cool it to room temperature, add modified montmorillonite and an antibacterial agent, stir, and then screen to obtain an environmentally friendly, degradable, and highly barrier emulsion.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The present invention uses polylactic acid as the main component of the barrier emulsion, and synthesizes an environmentally friendly, degradable, and highly barrier emulsion by adding modified montmorillonite, an antibacterial agent, etc. Through the synergistic effect among the components, the barrier emulsion has the characteristics of environmental friendliness, degradability, high barrier property, and high antibacterial property.

[0039] (2) The present invention uses erucic acid and monoethanolamine as raw materials, reacts them with phosphorus oxychloride, triethylamine, ethylene glycol, and octadecyldimethyl tertiary amine to obtain a substance with multiple hydrophilic and hydrophobic groups, and uses this substance to modify montmorillonite, effectively improving the dispersibility of montmorillonite, and introducing nanocellulose to mix and modify montmorillonite, further improving the oxygen barrier performance of montmorillonite.

[0040] (3) The present invention uses dicyandiamide to conduct guanidinylation modification on chitosan to obtain chitosan diguanide salt, and then grafts the chitosan diguanide salt on the surface of nano-titanium dioxide to prepare an antibacterial agent, which has the advantages of good dispersibility, good thermal stability, and excellent antibacterial property.

[0041] (4) The barrier emulsion prepared by the present invention has the characteristics of environmental friendliness, degradability, high barrier property, and high antibacterial property, and can be widely applied to the field of food packaging, having good commercial application value. Specific Embodiments

[0042] The following will illustrate the present invention in conjunction with specific implementation examples. It should be noted that the following examples are examples of the present invention, only used to illustrate the present invention, rather than to limit the present invention. Without departing from the main idea or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made.

[0043] In the following examples and comparative examples, except for modified montmorillonite and antibacterial agents, the other compound monomers and related reagents used can be purchased from the market. Among them, nanocellulose is purchased from Wuhan Lana White Pharmaceutical Chemical Co., Ltd.; chitosan is purchased from Qingdao Bozhihui Power Biotechnology Co., Ltd.

[0044] Preparation Example 1

[0045] The synthesis method of modified montmorillonite A includes the following steps:

[0046] (1) Add 35 g of erucic acid and 5 g of monoethanolamine to a reaction vessel. Under a nitrogen atmosphere, heat up to 165 °C, stir for 4.5 h, cool down to 60 °C, add 1.5 g of monoethanolamine and 0.1 g of sodium methoxide, heat up to 100 °C, and stir for 3.5 h to obtain Product 1 for standby;

[0047] (2) Mix 40 g of Product 1 from step (1), 40 ml of tetrahydrofuran, 40 ml of ether, and 40 ml of acetonitrile, stir for 20 min, add 18 g of phosphorus oxychloride, 10 g of triethylamine, 6 g of ethylene glycol, and 30 g of octadecyl dimethyl tertiary amine, stir at 0 °C for 4 h, heat up to 65 °C and stir for 36 h, recrystallize successively with n-hexane and isopropanol, and dry at 60 °C for 24 h to obtain Product 2 for standby;

[0048] (3) Add 10 g of montmorillonite to 100 ml of deionized water, stir for 1 h, add 8 g of Product 2 from step (2) and 10 g of nanocellulose, stir at 90 °C for 4 h, centrifuge, wash 3 times with absolute ethanol and deionized water respectively, and dry at 60 °C for 12 h to obtain modified montmorillonite A.

[0049] Preparation Example 2

[0050] For modified montmorillonite B, the specific implementation method is the same as that of modified montmorillonite A, except that: in step (1), the mass of erucic acid is replaced with 24 g.

[0051] Preparation Example 3

[0052] For modified montmorillonite C, the specific implementation method is the same as that of modified montmorillonite A, except that: in step (2), the mass of octadecyl dimethyl tertiary amine is replaced with 26 g.

[0053] Preparation Example 4

[0054] For modified montmorillonite D, the specific implementation method is the same as that of modified montmorillonite A, except that: in step (3), the mass of Product 2 is replaced with 5 g.

[0055] Preparation Example 5

[0056] For modified montmorillonite E, the specific implementation method is the same as that of modified montmorillonite A, except that: in step (3), the mass of nanocellulose is replaced with 7 g.

[0057] Preparation Example 6

[0058] The synthesis method of antibacterial agent A includes the following steps:

[0059] 1) Add 10 g of chitosan to 200 ml of 1 wt% hydrochloric acid aqueous solution, stir at 60 °C for 4 h, add 500 ml of 0.05 g / ml dicyandiamide aqueous solution, stir for 20 min, heat up to 95 °C, stir for 4 h, cool down to room temperature, add 300 ml of anhydrous ethanol at 0 °C for precipitation, centrifuge, add 200 ml of deionized water, dialyze, and freeze-dry at -40 °C for 12 h to obtain chitosan biguanide for standby;

[0060] 2) Add 10 g of nano-titanium dioxide to 450 ml of 75 wt% ethanol aqueous solution, ultrasonicate for 20 min to obtain Solution 1 for standby. Add 10 g of KH560 to 50 ml of 75 wt% ethanol aqueous solution, ultrasonicate for 15 min to obtain Solution 2 for standby. Mix Solution 1 and Solution 2, stir at 80 °C for 8 h, centrifuge, wash with deionized water and anhydrous ethanol three times in sequence, and dry at 60 °C for 24 h to obtain modified titanium dioxide for standby;

[0061] 3) Add 10 g of the chitosan biguanide from step 1) to 100 ml of deionized water, stir for 30 min to obtain Solution 3 for standby. Add 5 g of the modified titanium dioxide from step 2) to 200 ml of deionized water, ultrasonicate for 30 min, add Solution 3 and 0.1 g of tetramethylethylenediamine, stir at 50 °C for 6 h, centrifuge, wash with deionized water five times, and dry at 60 °C for 24 h to obtain antibacterial agent A.

[0062] Preparation Example 7

[0063] Antibacterial agent B, the specific implementation method is the same as that of antibacterial agent A, the difference is that: in step 1), the volume of the dicyandiamide aqueous solution is replaced with 380 ml.

[0064] Preparation Example 8

[0065] Antibacterial agent C, the specific implementation method is the same as that of antibacterial agent A, the difference is that: in step 3), the mass of the modified titanium dioxide is replaced with 3.7 g.

[0066] Example 1

[0067] An environmentally friendly, degradable and highly barrier emulsion. By weight, the barrier emulsion includes the following raw materials: 50 parts of L-lactide, 15 parts of ε-caprolactone, 7.5 parts of modified montmorillonite A, 2 parts of antibacterial agent A, 0.6 part of stannous octoate, 15 parts of ethyl acetate, 1.25 parts of Tween 40, and 250 parts of deionized water.

[0068] The preparation method of the environmentally friendly, degradable and highly barrier emulsion in this example includes the following steps:

[0069] S1. Add L-lactide into ethyl acetate, heat to 55 °C, stir for 30 min, then mix with ε-caprolactone, stir for 1 h, add Tween 40 and stannous octoate, stir for 30 min, add deionized water, and stir for 30 min to obtain an intermediate product for standby;

[0070] S2. Pass nitrogen into the intermediate product obtained in step S1, heat to 65 °C, stir for 2.5 h, cool down to room temperature, add modified montmorillonite A and antibacterial agent A, stir for 1 h, and pass through a 200-mesh sieve to obtain an environmentally friendly, degradable, and highly barrier emulsion.

[0071] Example 2

[0072] An environmentally friendly, degradable, and highly barrier emulsion, by weight, the barrier emulsion comprises the following raw materials: 40 parts of L-lactide, 10 parts of ε-caprolactone, 7.5 parts of modified montmorillonite A, 1 part of antibacterial agent A, 0.2 part of stannous octoate, 10 parts of ethyl acetate, 0.5 part of Tween 60, and 200 parts of deionized water.

[0073] The preparation method of the environmentally friendly, degradable, and highly barrier emulsion in this example comprises the following steps:

[0074] S1. Add L-lactide into ethyl acetate, heat to 50 °C, stir for 40 min, then mix with ε-caprolactone, stir for 1 h, add Tween 60 and stannous octoate, stir for 30 min, add deionized water, and stir for 30 min to obtain an intermediate product for standby;

[0075] S2. Pass nitrogen into the intermediate product obtained in step S1, heat to 60 °C, stir for 3 h, cool down to room temperature, add modified montmorillonite A and antibacterial agent A, stir for 1 h, and pass through a 200-mesh sieve to obtain an environmentally friendly, degradable, and highly barrier emulsion.

[0076] Example 3

[0077] An environmentally friendly, degradable, and highly barrier emulsion, by weight, the barrier emulsion comprises the following raw materials: 60 parts of L-lactide, 20 parts of ε-caprolactone, 7.5 parts of modified montmorillonite A, 3 parts of antibacterial agent A, 1 part of stannous octoate, 20 parts of ethyl acetate, 2 parts of Tween 60, and 300 parts of deionized water.

[0078] The preparation method of the environmentally friendly, degradable, and highly barrier emulsion in this example comprises the following steps:

[0079] S1. Add L-lactide into ethyl acetate, heat to 60 °C, stir for 20 min, then mix with ε-caprolactone, stir for 1 h, add Tween 60 and stannous octoate, stir for 30 min, add deionized water, and stir for 30 min to obtain an intermediate product for standby;

[0080] S2. Introduce an inert gas into the intermediate product of step S1, heat it to 70 °C, stir for 2 h, cool it to room temperature, add modified montmorillonite A and antibacterial agent A, stir for 1 h, and pass through a 200-mesh sieve to obtain an environmentally friendly, degradable, and highly barrier emulsion.

[0081] Example 4

[0082] An environmentally friendly, degradable, and highly barrier emulsion, by weight, the barrier emulsion comprises the following raw materials: 45 parts of L-lactide, 12 parts of ε-caprolactone, 5 parts of modified montmorillonite A, 2 parts of antibacterial agent A, 0.4 part of stannous octoate, 12 parts of ethyl acetate, 1 part of Tween 40, and 220 parts of deionized water.

[0083] In this example, the preparation method of the environmentally friendly, degradable, and highly barrier emulsion is the same as that in Example 1.

[0084] Example 5

[0085] An environmentally friendly, degradable, and highly barrier emulsion, by weight, the barrier emulsion comprises the following raw materials: 55 parts of L-lactide, 18 parts of ε-caprolactone, 10 parts of modified montmorillonite A10, 2 parts of antibacterial agent A, 0.8 part of stannous octoate, 18 parts of ethyl acetate, 1.5 parts of Tween 40, and 280 parts of deionized water.

[0086] In this example, the preparation method of the environmentally friendly, degradable, and highly barrier emulsion is the same as that in Example 1.

[0087] Example 6

[0088] This example provides an environmentally friendly, degradable, and highly barrier emulsion and its preparation method. The specific implementation method is the same as that in Example 1, except that modified montmorillonite B is used to replace modified montmorillonite A in equal amounts.

[0089] Example 7

[0090] This example provides an environmentally friendly, degradable, and highly barrier emulsion and its preparation method. The specific implementation method is the same as that in Example 1, except that modified montmorillonite C is used to replace modified montmorillonite A in equal amounts.

[0091] Example 8

[0092] This example provides an environmentally friendly, degradable, and highly barrier emulsion and its preparation method. The specific implementation method is the same as that in Example 1, except that modified montmorillonite D is used to replace modified montmorillonite A in equal amounts.

[0093] Example 9

[0094] This embodiment provides an environmentally friendly, degradable, and highly barrier emulsion and its preparation method. The specific implementation is the same as that of Example 1, except that modified montmorillonite E is used to replace modified montmorillonite A in equal amounts.

[0095] Example 10

[0096] This embodiment provides an environmentally friendly, degradable, and highly barrier emulsion and its preparation method. The specific implementation is the same as that of Example 1, except that antibacterial agent B is used to replace antibacterial agent A in equal amounts.

[0097] Example 11

[0098] This embodiment provides an environmentally friendly, degradable, and highly barrier emulsion and its preparation method. The specific implementation is the same as that of Example 1, except that antibacterial agent C is used to replace antibacterial agent A in equal amounts.

[0099] Example 12

[0100] This embodiment provides an environmentally friendly, degradable, and highly barrier emulsion and its preparation method. The specific implementation is the same as that of Example 1, except that chitosan is used to replace antibacterial agent A in equal amounts.

[0101] Example 13

[0102] This embodiment provides an environmentally friendly, degradable, and highly barrier emulsion and its preparation method. The specific implementation is the same as that of Example 1, except that nano-titanium dioxide is used to replace antibacterial agent A in equal amounts.

[0103] Comparative Example 1

[0104] This comparative example provides an environmentally friendly, degradable, and highly barrier emulsion and its preparation method. The specific implementation is the same as that of Example 1, except that montmorillonite is used to replace modified montmorillonite A.

[0105] Performance testing

[0106] The barrier and antibacterial properties of the environmentally friendly, degradable, and highly barrier emulsions of the above Examples 1-13 and Comparative Example 1 were tested, and the test results are shown in Table 1.

[0107] The barrier emulsions prepared in the examples and comparative examples were coated on a biaxially oriented polylactic acid film (BOPLA) with a coating thickness of 2 μm. After drying at room temperature, the film was obtained, and the barrier and antibacterial properties of the film were tested, using the biaxially oriented polylactic acid film (BOPLA) without coating the barrier emulsion as the control group.

[0108] (1) Barrier performance

[0109] The test was carried out through the oxygen transmission rate, referring to the standard GB / T 19789-2005.

[0110] (2) Antibacterial property

[0111] Refer to the standard QB / T 2591-2003

[0112] Table 1

[0113] Group <![CDATA[Oxygen transmission rate (cm 3 / m 2 ·24 h)]]> Antibacterial Rate (%) Example 1 18.5 99.9 Example 2 19.2 99.5 Example 3 18.9 99.4 Example 4 18.6 99.7 Example 5 18.7 99.6 Example 6 21.3 98.5 Example 7 21.5 98.2 Example 8 22.0 98.0 Example 9 22.2 98.0 Example 10 20.5 96.2 Example 11 20.7 95.9 Example 12 21.0 95.5 Example 13 20.9 95.0 Comparative Example 1 24.0 97.5 Control 27.5 /

[0114] It can be seen from the data in Table 1 that the environmentally friendly, degradable and highly barrier emulsion in Examples 1-5 of the present invention as a whole has good barrier and antibacterial properties. Among them, in Examples 6-9, the ratio between key components in the synthesis process of the modified montmorillonite was changed, so that the dispersibility and barrier property of the modified montmorillonite were not well improved, which in turn led to a significant decrease in the oxygen transmission rate of the barrier emulsion, but had little impact on the antibacterial property of the barrier emulsion; in Examples 10-11, the guanidination ratio of chitosan in the antibacterial agent and the modification ratio of chitosan biguanide to nano-titanium dioxide were changed, so that the antibacterial property and dispersibility of the antibacterial agent decreased, which in turn led to a significant decrease in the antibacterial property of the barrier emulsion, but had little impact on the barrier property; in Examples 12-13 and Comparative Example 1, chitosan and nano-titanium dioxide were respectively selected to replace antibacterial agent A and montmorillonite to replace modified montmorillonite A in equal amounts. Tests found that the barrier property of the environmentally friendly, degradable and highly barrier emulsion in Examples 12-13 and the antibacterial property of the environmentally friendly, degradable and highly barrier emulsion in Comparative Example 1 both showed poor results.

[0115] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it. It should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. An environmentally friendly, degradable, and highly barrier emulsion, characterized in that, By weight parts, the barrier emulsion comprises the following raw materials: 40 - 60 parts of L-lactide, 10 - 20 parts of ε-caprolactone, 5 - 10 parts of modified montmorillonite, 1 - 3 parts of antibacterial agent, 0.2 - 1 part of initiator, 10 - 20 parts of solvent, 0.5 - 2 parts of emulsifier, and 200 - 300 parts of deionized water; The modified montmorillonite is prepared by the following steps: (1) Add erucic acid and monoethanolamine 1 into a reaction vessel. Under an inert atmosphere, heat up to 160 - 170 °C, stir for 4 - 5 h, cool down to 50 - 70 °C, add monoethanolamine 2 and sodium methoxide, heat up to 90 - 110 °C, and stir for 3 - 4 h to obtain product 1 for standby; (2) Mix product 1 from step (1) with tetrahydrofuran, diethyl ether, and acetonitrile, stir, add phosphorus oxychloride, triethylamine, ethylene glycol, and octadecyl dimethyl tertiary amine, stir at -2~2 °C for 3 - 5 h, heat up to 60 - 70 °C and stir for 35 - 37 h, perform recrystallization, and dry to obtain product 2 for standby; (3) Add montmorillonite into deionized water, stir, add product 2 from step (2) and nanocellulose, stir at 80 - 100 °C for 3 - 5 h, centrifuge, wash, and dry to obtain the modified montmorillonite; The antibacterial agent is prepared by the following steps: 1) Add chitosan into an aqueous hydrochloric acid solution, stir at 50 - 70 °C for 3 - 5 h, add an aqueous dicyandiamide solution, stir, heat up to 90 - 100 °C, stir for 3 - 5 h, cool down to room temperature, precipitate, centrifuge, add deionized water, dialyze, and freeze-dry to obtain chitosan biguanide for standby; 2) Add nano-titanium dioxide into an aqueous ethanol solution, perform ultrasonic treatment to obtain solution 1 for standby. Add KH560 into an aqueous ethanol solution, perform ultrasonic treatment to obtain solution 2 for standby. Mix solution 1 and solution 2, stir at 70 - 90 °C for 7 - 9 h, centrifuge, wash, and dry to obtain pretreated titanium dioxide for standby; 3) Add the chitosan biguanide from step 1) into deionized water, stir to obtain solution 3 for standby. Add the pretreated titanium dioxide from step 2) into deionized water, perform ultrasonic treatment, add solution 3 and tetramethylethylenediamine, stir at 45 - 55 °C for 5 - 7 h, centrifuge, wash, and dry to obtain the antibacterial agent.

2. The environmentally friendly, degradable and highly barrier emulsion according to claim 1, wherein In step (1), the mass ratio of erucic acid to monoethanolamine 1 is 1:(0.1 - 0.2).

3. The environmentally friendly, biodegradable, and highly barrier emulsion according to claim 1, wherein In step (2), the mass ratio of product 1, phosphorus oxychloride, and octadecyl dimethyl tertiary amine is 1:(0.4 - 0.5):(0.7 - 0.8).

4. The environmentally friendly and biodegradable high-barrier emulsion according to claim 1, characterized in that, In step (3), the mass ratio of montmorillonite, product 2, and nanocellulose is 1:(0.6 - 1):(0.8 - 1.2).

5. The environmentally friendly, degradable, and highly barrier emulsion according to claim 1, wherein, In step 1), the mass ratio of chitosan to dicyandiamide in the aqueous dicyandiamide solution is 1:(2 - 3).

6. The environmentally friendly, degradable and highly barrier emulsion according to claim 1, wherein In step 3), the mass ratio of chitosan biguanide to pretreated titanium dioxide is 1:(0.4 - 0.6).

7. The environmentally friendly, degradable, and highly barrier emulsion according to claim 1, characterized in that, The emulsifier is Tween 40 or Tween 60.

8. A method for preparing the environmentally friendly, degradable and highly barrier emulsion according to any one of claims 1-7, characterized in that, Comprises the following steps: S1. Add L-lactide into a solvent, heat it to 50 - 60 °C, stir, mix it with ε-caprolactone, stir, add an emulsifier and an initiator, stir, add deionized water, and stir to obtain an intermediate product for standby; S2. Pass an inert gas into the intermediate product obtained in step S1, heat it to 60 - 70 °C, stir, cool it to room temperature, add modified montmorillonite and an antibacterial agent, stir, and sieve to obtain an environmentally friendly, degradable, and highly barrier emulsion.