CN110744880A

CN110744880A - High-breathability one-way moisture-resistant film for fruits and vegetables and preparation method thereof

Info

Publication number: CN110744880A
Application number: CN201910893625.8A
Authority: CN
Inventors: 邵平; 吴唯娜; 陈杭君; 郜海燕
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Zhejiang University of Technology ZJUT
Priority date: 2019-09-20
Filing date: 2019-09-20
Publication date: 2020-02-04
Anticipated expiration: 2039-09-20
Also published as: CN110744880B

Abstract

The invention discloses a high-permeability one-way moisture-blocking film for fruits and vegetables and a preparation method thereof, wherein the one-way moisture-blocking film consists of a hydrogel film layer and a spinning film layer and is prepared by the following method: preparing a carboxymethyl chitosan solution; weighing genipin, dissolving in pure water, adding into carboxymethyl chitosan solution dropwise, ultrasonic treating to disperse genipin in the solution uniformly, standing for 4-12 hr to complete crosslinking, and adding Ca (OH)₂And antibacterial substances, fully dispersing to obtain a hydrogel solution; pouring the hydrogel solution into a glass plate, putting the glass plate into a vacuum drying oven for drying, and taking off the glass plate to obtain a hydrogel film; and then taking ethyl cellulose and Tween-80 ethanol solution as spinning solution, and performing electrostatic spinning on the hydrogel film until the hydrogel film is completely covered by the spinning film layer to obtain the unidirectional moisture-blocking film. The unidirectional moisture-resistant film prepared by the invention can change gas permeability according to the respiration of fruits and vegetables, has good moisture-keeping and humidity-adjusting, waterproof and air-permeable and slow-release performances, and can effectively prolong the quality guarantee period of fruits and vegetables.

Description

High-breathability one-way moisture-resistant film for fruits and vegetables and preparation method thereof

(I) technical field

The invention belongs to the field of packaging materials, and particularly relates to a high-breathability one-way moisture-resistant film for fruits and vegetables and a preparation method thereof.

(II) technical background

Fruits play an important role in the daily dietary structure of people, but most fruits are extremely easy to decay, causing serious economic loss. Fruit rot caused by postharvest diseases in developed countries is generally lower than 5%, and the average loss rate of postharvest fruits in China is higher than 30%, so that the development of a safe and effective preservative and fresh-keeping technology for prolonging or maintaining the quality of fruits becomes an important food research subject.

The preservative film on the market mostly takes ethylene master batch as a raw material and is divided into three categories: polyethylene (PE), polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC), have the problem that causes environmental pollution and influences fruit vegetables edible scheduling, along with the rapid development of food science and technology and packaging industry, many novel packaging materials and packaging forms constantly appear, edible film based on biodegradable material is regarded as promising substitute, this type of film has compensatied the shortcoming in the aspect of pollution, but to the fresh-keeping not enough problem of gas permeability of fruit vegetables, the fruit vegetables can give out ripening ethylene gas, CO when placing itself, the fruit vegetables is gaseous, CO₂And water vapor, which occurs when the gas is not released due to accumulation and the moisture in the package is seriously condensedAnaerobic respiration accelerates the putrefaction of fruits and vegetables, and shortens the preservation time. Most of the existing preservative films for fruits and vegetables are used for realizing the respiration of the fruits and vegetables by punching holes on the preservative films, but the fruits and vegetables can be seriously dehydrated due to too fast volatilization of water, and the dehydration is equivalent to fresh loss and weight loss, so that the preservative films not only keep the water non-volatile, but also reduce the carbon dioxide in the preservative films when the content is too high. Therefore, a biodegradable fresh-keeping product which has good air permeability, can keep the moisture of fruits and vegetables, can prevent the moisture in the inner layer of a package from condensing and has good slow-release performance on antibacterial substances is needed.

Patent CN 108163369B discloses a one-way moisture-resistant multilayer edible film and a preparation method thereof, wherein a hydrophobic outer layer, a middle transition layer and a hydrophilic inner layer are used for preparing the one-way moisture-resistant film by adopting a tape casting method, but because the inner layer of the method adopts hydrophilic substances for directly preparing the film, the film is easy to dissolve when in contact with a large amount of water vapor, and the water storage performance is poor. Patent CN 105986511a discloses a method for manufacturing a fruit and vegetable humidity-regulating preservative film, wherein raw paper is made of plant fiber, and a mixed glue solution consisting of a hydrophilic water-retaining natural high molecular polymer and a non-water-soluble safe environment-friendly mildew-proof antibacterial agent is applied to prepare the humidity-regulating preservative film.

The traditional one-way moisture-resistant film has poor water storage capacity, short slow release time and insufficient film air permeability, so that the high-permeability film with the humidity-adjusting function for fruit and vegetable fresh-keeping has wide application prospect. The fruit and vegetable preservative is particularly suitable for the respiratory catastrophe fruits and vegetables which are easy to lose water, such as apricot, plum, fig, peach, pear, mango, blueberry, tomato, mushroom and the like.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a unidirectional moisture barrier film capable of changing gas permeability according to respiration of fruits and vegetables and having good moisture retention and conditioning functions for internal moisture retention and good water and gas permeability for external moisture retention, and a method for preparing the same.

In order to solve the technical problems, the invention adopts the following technical scheme:

the invention provides a unidirectional moisture barrier film, which consists of a hydrogel film layer and a spinning film layer;

the unidirectional moisture-resistant film is prepared by the following method: weighing 1.5-2 parts of carboxymethyl chitosan, dissolving in 100 parts of pure water, and stirring to completely dissolve the carboxymethyl chitosan to obtain a carboxymethyl chitosan solution; weighing 0.005-0.02 part of genipin, dissolving in 10 parts of pure water, adding into carboxymethyl chitosan solution dropwise, ultrasonic treating to uniformly disperse genipin in the solution, standing for 4-12h to complete crosslinking, and adding Ca (OH)₂0.02-0.05 part of antibacterial substance and 0.02-0.06 part of antibacterial substance, and fully dispersing to obtain a hydrogel solution; pouring the hydrogel solution into a glass plate, putting the glass plate into a vacuum drying oven for drying, and taking off the glass plate to obtain a hydrogel film; and then taking ethyl cellulose and Tween-80 ethanol solution as spinning solution, wherein the concentrations of the ethyl cellulose and the Tween-80 are respectively 10-30 wt% and 4-6 wt%, and performing electrostatic spinning on the hydrogel film until the hydrogel film is completely covered by the spinning film layer to obtain the unidirectional moisture-blocking film.

In the invention, the parts are all parts by mass.

The invention further provides a preparation method of the unidirectional moisture-resistant film, which comprises the following steps:

(1) weighing 1.5-2 parts of carboxymethyl chitosan, dissolving in 100 parts of pure water, and stirring to completely dissolve the carboxymethyl chitosan to obtain a carboxymethyl chitosan solution;

(2) weighing 0.005-0.02 part of genipin, dissolving in 10 parts of pure water in advance, dropwise adding into the carboxymethyl chitosan solution prepared in the step (1), performing ultrasonic treatment to uniformly disperse the genipin in the solution, standing for 4-12h to complete crosslinking, and adding Ca (OH)₂0.02-0.05 part of antibacterial substance and 0.02-0.06 part of antibacterial substance, and fully dispersing to obtain a hydrogel solution;

(3) pouring the hydrogel solution obtained in the step (2) into a glass plate, putting the glass plate into a vacuum drying oven for drying, and removing the glass plate to obtain a hydrogel film;

(4) weighing 1-3 parts of ethyl cellulose, dissolving the ethyl cellulose in 10 parts of ethanol, heating and stirring to completely dissolve the ethyl cellulose, adding Tween-80 to make the final concentration of the mixture be 4-6 wt%, and continuously stirring uniformly to obtain an ethyl cellulose spinning solution;

(5) placing the hydrogel film obtained in the step (3) on tin foil paper, fixing, and placing the fixed hydrogel film on a rotating roller receiving position of an electrostatic spinning machine to collect a spinning film;

(6) and (4) putting the spinning solution obtained in the step (4) into an injector, spinning by using an electrostatic spinning machine, wherein the type of a steel needle is 18G, the flow rate is 0.004-0.006ml/min, the receiving distance is 11-13cm, the voltage is 13-15KV, the ambient temperature of spinning is 30 +/-3 ℃, and the humidity is 40 +/-5% until the spinning film completely covers the hydrogel film, and finishing spinning to obtain the one-way moisture-blocking film.

Preferably, the bacteriostatic substance is tea polyphenol, cinnamaldehyde essential oil or oregano essential oil.

Preferably, in step (2), Ca (OH) is added₂And after antibacterial substances are added, magnetic stirring is carried out for 10-20min, and then ultrasonic treatment is carried out for 5-10min, so as to obtain the hydrogel solution.

Preferably, in step (3), the hydrogel solution is used in an amount per cm²Adding 0.1-0.3 part of hydrogel solution into the glass plate.

Preferably, in the step (3), the drying conditions in the vacuum drying oven are as follows: vacuum drying at 35-45 deg.C for 1-2d until oven drying.

In step 4 of the present invention, the ethyl cellulose can be dissolved in ethanol by means of heating and stirring.

The unidirectional moisture-resistant film prepared by the invention can be used as a fruit and vegetable preservative film, wherein the hydrogel film layer is in contact with the environment in the film, the spinning film layer is in contact with the external environment, the gas permeability can be changed according to the respiration of fruits and vegetables, and the unidirectional moisture-resistant film has good internal moisture-retention and humidity-control performance, good external waterproof and air permeability and good slow-release performance, and can effectively prolong the quality guarantee period of the fruits and vegetables.

By adopting the technology, compared with the prior art, the invention has the following beneficial effects:

(1) the invention adds Ca (OH) into the hydrogel water storage layer₂Moisture touch CO absorption₂Avoid CO in the package₂Is excessively accumulated.

In particular toIn other words, the traditional fruit and vegetable preservative film is often perforated in order to improve the air permeability, or CaCO is directly added₃However, such preservative films cannot change gas permeability according to fruit and vegetable respiration. Adding Ca (OH) to the hydrogel layer₂Initial hydrogel film in a dry state, Ca (OH)₂Can not absorb CO₂As respiration progresses, excess water vapor is absorbed into the hydrogel film, CO₂And also gradually increases, and carbon dioxide reacts with water in the hydrogel film to generate carbonic acid, in this case, Ca (OH)₂Can absorb CO₂Reaction to form CaCO₃，CaCO₃As a nonpolar and water-insoluble filler, when the two fillers are dispersed in hydrogel, the compatibility and the interface adhesion of the two fillers are poor, so that obvious defects exist between the two phases, the defects can enable gas molecules to permeate through a film, and for climacteric fruit and vegetable, a slow breathing period and a peak breathing period exist, and CO exists in the slow breathing period₂In a smaller amount of CaCO₃Less formation, insignificant increase in gas transmission rate, and CO at peak respiration₂And the moisture is increased rapidly, so that the preservative film has high gas permeability.

(2) The one-way moisture-blocking film consists of a hydrophilic moisture-preserving hydrogel water storage layer in contact with the environment in the package and a hydrophobic moisture-proof electrospun moisture-blocking layer in contact with the external environment, and has good moisture preservation, humidity regulation, water resistance, air permeability and slow release performance.

Specifically, hydrogel is used as a functional polymer material with a spatial three-dimensional cross-linked network structure, can keep high water content and keep the original structure without being dissolved, the hydrogel is used as a water storage layer, moisture or exudate generated by vegetable transpiration and physical and chemical changes in packaged food in the package is absorbed and stored when passing through the hydrogel layer, the absorbed moisture can be used for controlling the humidity of the interior of the package when the humidity in the package is low, and when water is absorbed and expanded, the mesh size of the polymer is increased, and the bacteriostatic agent is released. Although the conventional hydrophobic film prepared by the tape casting method has good moisture barrier capacity as an outer layer, the conventional hydrophobic film has poor air permeability and high brittleness, and the ethyl cellulose electrostatic spinning film is used as the hydrophobic outer layer, and due to the hydrophobicity, hydrogen bonds cannot be formed, the conventional hydrophobic film and water repel each other, moisture cannot be absorbed in the air, but a plurality of small holes are formed in the film, gas molecules can freely enter and exit the film, but due to the fact that water drops are large in size and have surface tension, moisture permeation from the environment outside the package can be prevented, the service life of an internal hydrogel water storage layer is effectively prolonged, the conventional hydrophobic film has high gas permeability, and the film is soft and firm and is more suitable for fruit and vegetable fresh keeping.

(3) The unidirectional moisture-resistant film prepared by the invention is used for preserving fruits and vegetables, can obviously improve the preservation effect and prolong the quality guarantee period of the fruits and vegetables.

Drawings

FIG. 1 is a technical scheme of a conventional scheme;

FIG. 2 is a technical scheme of the invention.

Detailed Description

The following examples are set forth in order to provide a thorough understanding of the invention and to provide a further understanding of the invention. However, the present invention is not limited by the following examples.

The various sources of raw materials used in the examples:

ethyl cellulose: 90-110mPa Shanghai Mecang Biotech, Inc.;

carboxymethyl chitosan: degree of substitution is not less than 80%, Shanghai Michelin Biochemical technology, Inc.;

genipin: 98%, Shanghai Michelin Biochemical technology, Inc.;

tween80 viscous liquid, Allantin reagent (Shanghai) Co., Ltd;

glycerol: 99%, west longa science, inc;

ethanol: 99.7%, Shanghai Michelin Biotechnology, Inc.;

calcium hydroxide: not less than 95%, 2000 mesh, Shanghai Michelin Biochemical technology Limited.

Example 1

(1) Weighing 1.5g of carboxymethyl chitosan, dissolving in 100g of pure water, and magnetically stirring for 4 hours at normal temperature to completely dissolve the carboxymethyl chitosan to obtain a carboxymethyl chitosan solution;

(2) weighing 0.02g of genipin, dissolving in 10g of pure water in advance, dropwise adding into the carboxymethyl chitosan solution prepared in the step 1, carrying out ultrasonic water bath treatment for 10min to uniformly disperse the genipin in the solution, carrying out ultrasonic frequency of 40KHz and ultrasonic power of 360W, standing for 4h to complete crosslinking, and adding Ca (OH)₂0.05g of origanum vulgare essential oil and 0.06g of magnetic stirring for 10min, and carrying out ultrasonic treatment for 10min to obtain a hydrogel solution;

(3) pouring the hydrogel solution obtained in the step (2) into a 24 x 24cm glass plate, putting the glass plate into a vacuum drying oven, drying the glass plate for 1 to 2 days at the temperature of 45 ℃, and removing the glass plate to obtain a hydrogel film;

(4) weighing 3g of ethyl cellulose, dissolving the ethyl cellulose in 10g of ethanol, heating and stirring to completely dissolve the ethyl cellulose, adding Tween-80 to make the final concentration of the ethyl cellulose be 4%, and continuously stirring for 10min to obtain an ethyl cellulose spinning solution;

(5) placing the hydrogel film obtained in the step (3) on tin foil paper, fixing, and placing the fixed hydrogel film on a receiving part of a rotating roller to collect a spinning film;

(6) and (3) putting the spinning solution obtained in the step (4) into a 5ml syringe, spinning by using an electrostatic spinning machine, wherein the type of a steel needle is 18G, the flow rate is 0.004ml/min, the receiving distance is 11cm, the voltage is 13KV, the ambient temperature of spinning is 30 +/-3 ℃, and the humidity is 40 +/-5% until the surface of the hydrogel membrane is completely covered by the electrostatic spinning membrane, and stopping spinning to obtain the one-way moisture-blocking membrane.

Example 2

(1) Weighing 2g of carboxymethyl chitosan, dissolving in 100g of pure water, and magnetically stirring for 4 hours at normal temperature to completely dissolve the carboxymethyl chitosan to obtain a carboxymethyl chitosan solution;

(2) weighing 0.005g of genipin, dissolving the genipin in 10g of pure water in advance, dropwise adding the solution into the carboxymethyl chitosan solution prepared in the step (1), carrying out ultrasonic water bath treatment for 10min to uniformly disperse the genipin in the solution, carrying out ultrasonic frequency of 40KHz and ultrasonic power of 360W, standing the solution for 8h to complete crosslinking, and adding Ca (OH)₂0.02g of tea polyphenol and 0.05g of tea polyphenol, magnetically stirring for 15min, and carrying out ultrasonic treatment for 5min to obtain a hydrogel solution;

(3) pouring the hydrogel solution obtained in the step (2) into a 24 x 24cm glass plate, putting the glass plate into a vacuum drying oven, drying the glass plate for 1 to 2 days at 40 ℃, and removing the glass plate to obtain a hydrogel film;

(4) weighing 1g of ethyl cellulose, dissolving the ethyl cellulose in 10g of ethanol, heating and stirring to completely dissolve the ethyl cellulose, adding Tween-80 to make the final concentration of the ethyl cellulose to be 6%, and continuously stirring for 10min to obtain an ethyl cellulose spinning solution;

(6) and (3) putting the spinning solution obtained in the step (4) into a 5ml injector, spinning by using an electrostatic spinning machine, wherein the type of a steel needle is 18G, the flow rate is 0.006ml/min, the receiving distance is 13cm, the voltage is 14KV, the ambient temperature of spinning is 30 +/-3 ℃, and the humidity is 40 +/-5% until the surface of the hydrogel film is completely covered by the electrostatic spinning film, and stopping spinning to obtain the one-way moisture-blocking film.

Example 3

(1) Weighing 1.8g of carboxymethyl chitosan, dissolving in 100g of pure water, and magnetically stirring for 4 hours at normal temperature to completely dissolve the carboxymethyl chitosan to obtain a carboxymethyl chitosan solution;

(2) weighing 0.01g of genipin, dissolving in 10g of pure water in advance, dropwise adding into the carboxymethyl chitosan solution prepared in the step 1, performing ultrasonic water bath treatment for 10min to uniformly disperse the genipin in the solution, performing ultrasonic frequency of 40KHZ and ultrasonic power of 360W, standing for 12h to complete crosslinking, and adding Ca (OH)₂0.04g of cinnamyl aldehyde essential oil and 0.02g of cinnamyl aldehyde essential oil, magnetically stirring for 20min, and carrying out ultrasonic treatment for 8min to obtain a hydrogel solution;

(3) pouring the hydrogel solution obtained in the step (2) into a 24 x 24cm glass plate, putting the glass plate into a vacuum drying oven, drying the glass plate for 1 to 2 days at the temperature of 35 ℃, and removing the glass plate to obtain a hydrogel film;

(4) weighing 2g of ethyl cellulose, dissolving the ethyl cellulose in 10g of ethanol, heating and stirring to completely dissolve the ethyl cellulose, adding Tween-80 to make the final concentration of the ethyl cellulose to be 5%, and continuously stirring for 10min to obtain an ethyl cellulose spinning solution;

(6) and (3) putting the spinning solution obtained in the step (4) into a 5ml injector, spinning by using an electrostatic spinning machine, wherein the type of a steel needle is 18G, the flow rate is 0.005ml/min, the receiving distance is 12cm, the voltage is 15KV, the ambient temperature of spinning is 30 +/-3 ℃, and the humidity is 40 +/-5% until the surface of the hydrogel membrane is completely covered by the electrostatic spinning membrane, and stopping spinning to obtain the one-way moisture-blocking membrane.

The testing method of the membrane obtained in the embodiment of the invention is as follows:

(1) the water vapor transmission rate determination method comprises the following steps: cutting the film into a circle with the radius of 50mm, testing by using a water vapor transmission rate analyzer, testing each group of samples for 5 times, taking an average value, and testing the water vapor transmission rate every other day after preservation for 3 days.

Method for measuring gas permeability: referring to GB/T1038-2000, the gas permeability is tested every other day after preservation for 3 days.

The results are shown in table 1:

	water vapor transmission rate	Initial CO₂Transmittance of light	Initial O₂Transmittance of light
				Example 1	579g/m²·d	657mL/(m²·d·0.1MPa)	204mL/(m²·d·0.1MPa)
Example 2	591g/m²·d	732mL/(m²·d·0.1MPa)	184mL/(m²·d·0.1MPa)
				Example 3	535g/m²·d	638mL/(m2·d·0.1MPa)	218mL/(m²·d·0.1MPa)

	Water vapor transmission rate on the second day	Second day CO₂Transmittance of light	The next day O₂Transmittance of light
				Example 1	629g/m²·d	2657mL/(m²·d·0.1MPa)	933mL/(m²·d·0.1MPa)
Example 2	701g/m²·d	2732mL/(m²·d·0.1MPa)	1189mL/(m²·d·0.1MPa)
				Example 3	635g/m²·d	2638mL/(m2·d·0.1MPa)	1074mL/(m²·d·0.1MPa)

TABLE 1

	Water vapor transmission rate on the third day	Third day CO₂Transmittance of light	Day three O₂Transmittance of light
				Example 1	819g/m²·d	5057mL/(m²·d·0.1MPa)	1914mL/(m²·d·0.1MPa)
Example 2	791g/m²·d	4932mL/(m²·d·0.1MPa)	1874mL/(m²·d·0.1MPa)
				Example 3	835g/m²·d	5638mL/(m²·d·0.1MPa)	2017mL/(m²·d·0.1MPa)

The obtained film is used for carrying out fruit and vegetable fresh-keeping experiments, and the agaricus bisporus is taken as an example, and the test method comprises the following steps:

fresh agaricus bisporus was purchased from Hangzhou farmer markets, mechanically damaged samples were removed, randomly divided into 3 groups of 3 parallel boxes each containing 6 samples. The fresh-keeping treatment is carried out by adopting three treatment modes, wherein the first mode is that no packaging treatment is carried out, the second mode is that the film obtained by the previous preparation is used for packaging, and the third mode is that the LDPE fresh-keeping film commonly used in the market is used for packaging. Meanwhile, in order to simulate the actual storage temperature of the mushrooms in the market, the mushrooms were stored in a room at a room temperature of 20 ℃ for 3 days, and the quality change of the agaricus bisporus was measured.

(1) The weight loss rate measuring method comprises the following steps: and (3) measuring the weight loss rate of the mushrooms after being stored for 3 days by adopting a weighing method. The calculation formula is as follows:

where M0 is the mass of the initial mushroom and M is the mass that is called for each sampling day.

(2) The hardness measuring method comprises the following steps:

hardness test of mushrooms with a TAXT. plus texture analyzer, selecting a P/2 probe with a diameter of 2mm, and setting parameters as follows: the puncture speed is 10mm/s, the puncture depth is 5mm, and the maximum pressure in the puncture process represents the hardness of the agaricus bisporus epidermis. At least three different points were selected for each sample and averaged.

The results are shown in table 2:

TABLE 2

	Weight loss ratio	Hardness of	Good fruit rate
				Initial	0％	400g	-
Without packaging	70％	263g	0
				LDPE film	7.5％	237g	30％
Example 1	6.7％	314g	100％
				Example 2	7.2％	308g	100％
Example 3	7.9％	321g	100％

Claims

1. A one-way moisture barrier film, characterized in that: the unidirectional moisture-blocking film consists of a hydrogel film layer and a spinning film layer;

the unidirectional moisture-resistant film is prepared by the following method: weighing 1.5-2 parts of carboxymethyl chitosan, dissolving in 100 parts of pure water, and stirring to completely dissolve the carboxymethyl chitosan to obtain a carboxymethyl chitosan solution; weighing 0.005-0.02 part of genipin, dissolving in 10 parts of pure water, adding into carboxymethyl chitosan solution dropwise, ultrasonic treating to uniformly disperse genipin in the solution, standing for 4-12h to complete crosslinking, and adding Ca (OH)₂0.02-0.05 part of antibacterial substance and 0.02-0.06 part of antibacterial substance, and fully dispersing to obtain a hydrogel solution; pouring the hydrogel solution into a glass plate, putting the glass plate into an oven for drying, and removing the glass plate to obtain a hydrogel film; and then taking ethyl cellulose and Tween-80 ethanol solution as spinning solution, wherein the concentrations of the ethyl cellulose and the Tween-80 are respectively 10-30 wt% and 4-6 wt%, and performing electrostatic spinning on the hydrogel film until the hydrogel film is completely covered by the spinning film layer to obtain the unidirectional moisture-blocking film.

2. A method of making a unidirectional moisture barrier film as defined in claim 1, comprising the steps of:

3. The method of claim 2, wherein: the antibacterial substance is tea polyphenol, cinnamaldehyde essential oil, and oregano essential oil.

4. The production method according to claim 2 or 3, characterized in that: in the step (3), the dosage of the hydrogel solution is calculated according to per cm²Adding 0.1-0.3 part of hydrogel solution into the glass plate.

5. The production method according to claim 2 or 3, characterized in that: in the step (2), Ca (OH) is added₂And after antibacterial substances are added, magnetic stirring is carried out for 10-20min, and then ultrasonic treatment is carried out for 5-10min, so as to obtain the hydrogel solution.

6. The production method according to claim 2 or 3, characterized in that: in the step (3), the drying conditions in the oven are as follows: vacuum drying at 35-45 deg.C for 1-2d until oven drying.