阅读说明：本技术 控释型可降解活性包装薄膜及其制备方法和应用 (Controlled release degradable active packaging film and preparation method and application thereof ) 是由 陈晨伟 宗琳 陈丽君 谢晶 杨福馨 于 2020-12-30 设计创作，主要内容包括：本发明提供了一种控释型可降解活性包装薄膜及其制备方法和应用,该薄膜的多层复合结构中内层为含有甘油的醋酸纤维素薄膜,中间层为由活性物质组成的淀粉/聚乙烯醇薄膜,外层为聚乳酸薄膜或聚己二酸/对苯二甲酸丁二酯薄膜,活性物质包括抗菌剂和抗氧化剂；本发明的内层薄膜中甘油与醋酸纤维素相互作用,在醋酸纤维素薄膜内部形成塑化区,在具有一定压强的水流作用下,可形成具有纳米孔隙的薄膜,孔隙率随着甘油含量的增加而增加,从而增加了薄膜的透过性,加速了中间层活性物质的释放；同时,醋酸纤维素薄膜中形成的空隙大小和孔隙率随着水流压强的增大而增大,从而增加了薄膜的透过性,也加速了活性物质的释放。(The invention provides a controlled-release degradable active packaging film and a preparation method and application thereof, wherein the inner layer of a multilayer composite structure of the film is a cellulose acetate film containing glycerol, the middle layer is a starch/polyvinyl alcohol film consisting of active substances, the outer layer is a polylactic acid film or a polybutylene adipate/terephthalate film, and the active substances comprise an antibacterial agent and an antioxidant; according to the invention, glycerol and cellulose acetate interact in the inner layer film, a plasticizing area is formed in the cellulose acetate film, the film with nano pores can be formed under the action of water flow with certain pressure, and the porosity is increased along with the increase of the content of the glycerol, so that the permeability of the film is increased, and the release of active substances in the middle layer is accelerated; meanwhile, the size and porosity of the gaps formed in the cellulose acetate film are increased along with the increase of the water flow pressure, so that the permeability of the film is increased, and the release of active substances is accelerated.)

1. A controlled release degradable active packaging film, which is characterized in that: the composite material is prepared by compounding an inner layer, a middle layer and an outer layer; the inner layer is a cellulose acetate film containing glycerin, the middle layer is a starch/polyvinyl alcohol film consisting of active substances, and the outer layer is a degradable film;

the degradable film is selected from more than one of polylactic acid film and polybutylene adipate/terephthalate film;

the active substance is selected from more than one of an antibacterial agent and an antioxidant.

2. The controlled release, degradable active packaging film of claim 1 wherein: the content of the cellulose acetate film in the inner layer is 67-95 wt%, and the content of the glycerol is 5-33 wt%.

3. The controlled release, degradable active packaging film of claim 1 wherein: the content of active substances in the middle layer is 1-15 wt%, the antibacterial agent is sodium lactate, and the antioxidant is anthocyanin.

4. A method for preparing the controlled release degradable active packaging film according to any one of claims 1 to 3, wherein the method comprises the following steps: which comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film containing glycerin: preparing an acetone aqueous solution with a mass ratio of 9:1, mixing and dissolving cellulose acetate, glycerol and the acetone aqueous solution to obtain a first mixed solution, flatly paving the first mixed solution on a glass plate and drying to obtain a glycerin-containing cellulose acetate film, enabling water to flow through the cellulose acetate film, and drying the film, wherein the pressure of water is 0.3-0.8 MPa;

(2) preparing an intermediate layer:

preparing starch/polyvinyl alcohol film liquid containing active substances: weighing starch, mixing with water and dissolving to obtain a starch solution, weighing polyvinyl alcohol resin, mixing with water and dissolving to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding glycerol and citric acid, and mixing to obtain a second mixed solution; then cooling the second mixed solution to 45 ℃, adding an active substance into the second mixed solution, mixing the active substance in a water bath at 45 ℃, and carrying out ultrasonic treatment for standby application;

(3) and preparing a three-layer composite film:

tiling the cellulose acetate film containing glycerin prepared in the step (1) on a glass plate, tiling the starch/polyvinyl alcohol film liquid containing active substances prepared in the step (2) on the cellulose acetate film, and drying to obtain a composite film;

and (3) carrying out dry compounding on the outer degradable film and the composite film to obtain the controlled-release degradable active packaging film.

5. The method of claim 4, wherein: in the step (1), the drying temperature is 25 +/-1 ℃, and the drying time is 15 +/-1 min.

6. The method of claim 4, wherein: in the step (2), the temperature for mixing and dissolving is 95 +/-1 ℃.

7. The method of claim 4, wherein: in the step (2), the active substance is selected from more than one of an antibacterial agent and an antioxidant.

8. The method of claim 7, wherein: the antibacterial agent is sodium lactate, and the antioxidant is anthocyanin.

9. The method of claim 4, wherein: in the step (3), the drying temperature is 45 +/-1 ℃, and the drying time is 1 +/-0.1 h;

preferably, in the step (3), the degradable film is selected from one or more of a polylactic acid film and a polybutylene adipate/terephthalate film.

10. Use of the controlled release degradable active packaging film of claim 1 in food packaging.

Technical Field

The invention belongs to the technical field of composite films, and particularly relates to a controlled-release degradable active packaging film, a preparation method and application thereof, in particular to a multilayer composite controlled-release degradable active packaging film regulated and controlled by a cellulose acetate film containing glycerol in the inner layer, and a preparation method and application thereof.

Background

Compared with the traditional food packaging technology, the active packaging technology has incomparable advantages, can improve the food quality and prolong the shelf life of the food, has become a hotspot of domestic and foreign researches, and the research on active packaging film materials is one of the researches. The active packaging film is mainly prepared by adding active substances into a polymer, so that the prepared film has the functions of antibiosis, antioxidation and the like, can effectively inhibit the putrefaction of food, and achieves the effect of prolonging the shelf life of the food. In addition, due to the exhaustion of petroleum resources and the increasing problem of environmental pollution, degradable packaging film materials become the focus of research and development at home and abroad. The starch and the PVA are degradable high polymer materials, and researches show that the starch/PVA film has better mechanical property, transparency, gas barrier property and the like, is widely applied to the fields of food packaging, agriculture, biological medicine and pharmacology and the like, and is a green and sustainable production material capable of replacing petroleum-based packaging. The controlled release active packaging film is a type of active packaging, and is prepared by taking a film material as a base material, adding active substances such as an antibacterial agent, an antioxidant and the like into the film base material and preparing the active film with the functions of antibiosis, antioxidation and the like by a film forming technology. The effective acting time of the active substance is adjusted by regulating and controlling the release rate of the active substance to ensure that the active substance is slowly and continuously released, thereby prolonging the shelf life of the food. Patent CN 107379703B discloses a controlled release active packaging film and a preparation method thereof, the film is a multilayer composite structure, and is composed of an inner layer, a middle layer and an outer layer, and the permeability of the inner layer film is adjusted by the inner layer laser drilling process, so as to control the release rate of active substances in the middle active layer and achieve the purpose of controlled release.

Disclosure of Invention

Aiming at the defects in the prior art, the primary object of the invention is to provide a controlled-release degradable active packaging film.

The second purpose of the invention is to provide a preparation method of the controlled-release degradable active packaging film.

Another object of the present invention is to provide the use of the above-mentioned controlled release degradable active packaging film.

In order to achieve the above primary object, the solution of the present invention is:

a controlled release degradable active packaging film is a multilayer composite structure, and is specifically prepared by compounding an inner layer, a middle layer and an outer layer; the inner layer is a cellulose acetate film containing glycerin, the middle layer is a starch/polyvinyl alcohol film consisting of active substances, and the outer layer is a degradable film selected from more than one of a polylactic acid film and a polybutylene adipate/terephthalate film.

The active substance is selected from more than one of antibacterial agent and antioxidant.

Preferably, the content of the cellulose acetate film in the inner layer is 67-95 wt%, and the content of glycerin is 5-33 wt%.

Preferably, the content of the active material in the intermediate layer is 1 to 15 wt%. The antibacterial agent is sodium lactate, and the antioxidant is anthocyanidin.

In order to achieve the second objective, the solution of the invention is:

the preparation method of the controlled-release degradable active packaging film comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film containing glycerin: preparing an acetone aqueous solution with the mass ratio of 9:1, mixing 10 +/-0.1 g of cellulose acetate, glycerol and the acetone aqueous solution, stirring at normal temperature until the mixture is dissolved to obtain a first mixed solution, spreading the first mixed solution on a glass plate, drying at 25 +/-1 ℃ for 15 +/-1 min, then removing the first mixed solution from the glass plate to obtain a cellulose acetate film containing the glycerol, then putting the cellulose acetate film into a high-pressure water equipment flow channel to enable water to flow through the film for 1h, wherein the pressure of water is 0.3-0.8MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol film liquid containing active substances: weighing 4 +/-0.1 g of corn starch, mixing the corn starch with water, stirring the mixture in a water bath at the temperature of 95 +/-1 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4 +/-0.1 g of polyvinyl alcohol (PVA) resin, mixing the mixture with water, and stirring the mixture in the water bath at the temperature of 95 +/-1 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, then adding 1.2 +/-0.01 g of glycerol and 1.2 +/-0.01 g of citric acid, mixing, and stirring in a water bath at the temperature of 95 +/-1 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 1.2 +/-0.01 g of active substances, stirring in a water bath at 45 ℃ until the active substances are uniformly mixed, and then ultrasonically defoaming for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film containing glycerin prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing the active substances prepared in the step (2) on the cellulose acetate film, and drying the cellulose acetate film for 1 +/-0.1 h at the temperature of 45 +/-1 ℃ to obtain a composite film;

and (3) carrying out a dry compounding process on the outer polylactic acid film or the poly adipic acid/butylene terephthalate film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

In the step (2), the active substance is selected from more than one of an antibacterial agent and an antioxidant, wherein the antibacterial agent is sodium lactate, and the antioxidant is anthocyanin.

In order to achieve the other purpose, the solution of the invention is as follows:

the degradable active packaging film of the controlled release type can be applied to food packaging.

Due to the adoption of the scheme, the invention has the beneficial effects that:

firstly, glycerin and cellulose acetate in the inner layer film interact with each other to form a plasticizing area in the cellulose acetate film, and the film with nano pores can be formed under the action of water flow with certain pressure, wherein the porosity is increased along with the increase of the content of the glycerin, so that the permeability of the film is increased, and the release of active substances in the middle layer is accelerated; meanwhile, the size and porosity of the gaps formed in the cellulose acetate film are increased along with the increase of the water flow pressure, so that the permeability of the film is increased, and the release of the active substances is accelerated.

Secondly, the controlled-release degradable active packaging film takes a degradable material as a film base material, the film is of a multilayer composite structure and comprises an inner layer, a middle layer and an outer layer, the film is based on the multilayer composite controlled-release principle, a starch/PVA active film layer is taken as the middle layer, a cellulose acetate film containing glycerin is taken as the inner layer material, the outer layer is a polylactic acid film or a poly adipic acid/butylene terephthalate film and other degradable films, the multilayer composite film is prepared, the release of antibacterial, antioxidant and other active substances can be regulated and controlled by regulating the permeability of the inner layer cellulose acetate film, the controlled-release effect is achieved, and therefore, the controlled-release degradable active packaging film is applied to food packaging, is more beneficial to protecting food and prolonging the shelf life of the food, and is green and.

Drawings

Fig. 1 is a graph showing the release amount of sodium lactate from the film into the food simulant (water) with time in the films according to the example of the present invention and the comparative example.

Fig. 2 is a graph showing the release amount of anthocyanin in the film from the film into the food simulant (water) according to the example of the present invention and the comparative example, as a function of time.

Detailed Description

The invention provides a controlled-release degradable active packaging film and a preparation method and application thereof.

The present invention will be further described with reference to examples and comparative examples.

Example 1:

the preparation method of the controlled release degradable active packaging film of the embodiment comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film containing 5 wt% of glycerin: preparing an acetone aqueous solution with a mass ratio of 9:1, mixing 10g of cellulose acetate, 0.53g of glycerol and 90g of the acetone aqueous solution, and stirring at normal temperature until the mixture is dissolved to obtain a first mixed solution; spreading the first mixed solution on a glass plate, drying at 25 ℃ for 15min, and then removing the glass plate to obtain a cellulose acetate film containing glycerol; and then putting the cellulose acetate film into a flow channel of high-pressure water equipment to enable water flow to pass through the film for 1h, wherein the pressure intensity of water is 0.8MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol film liquid containing sodium lactate: weighing 4g of corn starch, mixing with 50g of water, stirring in a water bath at 95 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4g of polyvinyl alcohol (PVA) resin, mixing with 50g of water, and stirring in the water bath at 95 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding 1.2g of glycerol and 1.2g of citric acid, mixing, and stirring in a water bath at 95 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 1.2g of sodium lactate (used as an antibacterial agent) into the second mixed solution, stirring the mixture in a water bath at 45 ℃ until the mixture is uniformly mixed, and then ultrasonically defoaming the mixture for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film containing glycerin prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing sodium lactate prepared in the step (2) on the cellulose acetate film, and drying the cellulose acetate film liquid at the temperature of 45 ℃ for 1h to obtain a composite film;

and (3) carrying out a dry compounding process on the outer polylactic acid film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

Example 2:

the preparation method of the controlled release degradable active packaging film of the embodiment comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film containing 33 wt% of glycerol: preparing an acetone aqueous solution with a mass ratio of 9:1, mixing 10g of cellulose acetate, 5g of glycerol and 90g of the acetone aqueous solution, and stirring at normal temperature until the mixture is dissolved to obtain a first mixed solution; spreading the first mixed solution on a glass plate, drying at 25 ℃ for 15min, and then removing the glass plate to obtain a cellulose acetate film containing glycerol; and then putting the cellulose acetate film into a flow channel of high-pressure water equipment to enable water flow to pass through the film for 1h, wherein the pressure intensity of water is 0.8MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol film liquid containing sodium lactate: weighing 4g of corn starch, mixing with 50g of water, stirring in a water bath at 95 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4g of polyvinyl alcohol (PVA) resin, mixing with 50g of water, and stirring in the water bath at 95 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding 1.2g of glycerol and 1.2g of citric acid, mixing, and stirring in a water bath at 95 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 1.2g of sodium lactate (used as an antibacterial agent) into the second mixed solution, stirring the mixture in a water bath at 45 ℃ until the mixture is uniformly mixed, and then ultrasonically defoaming the mixture for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film containing glycerin prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing sodium lactate prepared in the step (2) on the cellulose acetate film, and drying the cellulose acetate film liquid at the temperature of 45 ℃ for 1h to obtain a composite film;

and (3) carrying out a dry compounding process on the outer polylactic acid film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

Example 3:

the preparation method of the controlled release degradable active packaging film of the embodiment comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film containing 33 wt% of glycerol: preparing an acetone aqueous solution with a mass ratio of 9:1, mixing 10g of cellulose acetate, 5g of glycerol and 90g of the acetone aqueous solution, and stirring at normal temperature until the mixture is dissolved to obtain a first mixed solution; spreading the first mixed solution on a glass plate, drying at 25 ℃ for 15min, and then removing the glass plate to obtain a cellulose acetate film containing glycerol; and then putting the cellulose acetate film into a flow channel of high-pressure water equipment to enable water flow to pass through the film for 1h, wherein the pressure intensity of water is 0.3MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol film liquid containing sodium lactate: weighing 4g of corn starch, mixing with 50g of water, stirring in a water bath at 95 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4g of polyvinyl alcohol (PVA) resin, mixing with 50g of water, and stirring in the water bath at 95 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding 1.2g of glycerol and 1.2g of citric acid, mixing, and stirring in a water bath at 95 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 1.2g of sodium lactate (used as an antibacterial agent) into the second mixed solution, stirring the mixture in a water bath at 45 ℃ until the mixture is uniformly mixed, and then ultrasonically defoaming the mixture for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film containing glycerin prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing sodium lactate prepared in the step (2) on the cellulose acetate film, and drying the cellulose acetate film liquid at the temperature of 45 ℃ for 1h to obtain a composite film;

and (3) carrying out a dry compounding process on the outer polylactic acid film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

Example 4:

the preparation method of the controlled release degradable active packaging film of the embodiment comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film containing 33 wt% of glycerol: preparing an acetone aqueous solution with a mass ratio of 9:1, mixing 10g of cellulose acetate, 5g of glycerol and 90g of the acetone aqueous solution, and stirring at normal temperature until the mixture is dissolved to obtain a first mixed solution; spreading the first mixed solution on a glass plate, drying at 25 ℃ for 15min, and then removing the glass plate to obtain a cellulose acetate film containing glycerol; and then putting the cellulose acetate film into a flow channel of high-pressure water equipment to enable water flow to pass through the film for 1h, wherein the pressure intensity of water is 0.5MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol film liquid containing sodium lactate: weighing 4g of corn starch, mixing with 50g of water, stirring in a water bath at 95 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4g of polyvinyl alcohol (PVA) resin, mixing with 50g of water, and stirring in the water bath at 95 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding 1.2g of glycerol and 1.2g of citric acid, mixing, and stirring in a water bath at 95 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 1.2g of sodium lactate (used as an antibacterial agent) into the second mixed solution, stirring the mixture in a water bath at 45 ℃ until the mixture is uniformly mixed, and then ultrasonically defoaming the mixture for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film containing glycerin prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing sodium lactate prepared in the step (2) on the cellulose acetate film, and drying the cellulose acetate film liquid at the temperature of 45 ℃ for 1h to obtain a composite film;

and (3) carrying out a dry compounding process on the outer polylactic acid film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

Example 5:

the preparation method of the controlled release degradable active packaging film of the embodiment comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film containing 5 wt% of glycerin: preparing an acetone aqueous solution with a mass ratio of 9:1, mixing 10g of cellulose acetate, 0.53g of glycerol and 90g of the acetone aqueous solution, and stirring at normal temperature until the mixture is dissolved to obtain a first mixed solution; spreading the first mixed solution on a glass plate, drying at 25 ℃ for 15min, and then removing the glass plate to obtain a cellulose acetate film containing glycerol; and then putting the cellulose acetate film into a flow channel of high-pressure water equipment to enable water flow to pass through the film for 1h, wherein the pressure intensity of water is 0.8MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol membrane liquid containing anthocyanin: weighing 4g of corn starch, mixing with 50g of water, stirring in a water bath at 95 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4g of polyvinyl alcohol (PVA) resin, mixing with 50g of water, and stirring in the water bath at 95 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding 1.2g of glycerol and 1.2g of citric acid, mixing, and stirring in a water bath at 95 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 1.2g of anthocyanin (serving as an antioxidant) into the second mixed solution, stirring the mixture in a water bath at 45 ℃ until the mixture is uniformly mixed, and then ultrasonically defoaming the mixture for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film containing the glycerol prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing the anthocyanin prepared in the step (2) on the cellulose acetate film, and drying the cellulose acetate film for 1 hour at the temperature of 45 ℃ to obtain a composite film;

and (3) carrying out a dry compounding process on the outer layer of the polybutylene adipate/terephthalate film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

Example 6:

the preparation method of the controlled release degradable active packaging film of the embodiment comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film containing 33 wt% of glycerol: preparing an acetone aqueous solution with a mass ratio of 9:1, mixing 10g of cellulose acetate, 5g of glycerol and 90g of the acetone aqueous solution, and stirring at normal temperature until the mixture is dissolved to obtain a first mixed solution; spreading the first mixed solution on a glass plate, drying at 25 ℃ for 15min, and then removing the glass plate to obtain a cellulose acetate film containing glycerol; and then putting the cellulose acetate film into a flow channel of high-pressure water equipment to enable water flow to pass through the film for 1h, wherein the pressure intensity of water is 0.8MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol membrane liquid containing anthocyanin: weighing 4g of corn starch, mixing with 50g of water, stirring in a water bath at 95 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4g of polyvinyl alcohol (PVA) resin, mixing with 50g of water, and stirring in the water bath at 95 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding 1.2g of glycerol and 1.2g of citric acid, mixing, and stirring in a water bath at 95 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 1.2g of anthocyanin (serving as an antioxidant) into the second mixed solution, stirring the mixture in a water bath at 45 ℃ until the mixture is uniformly mixed, and then ultrasonically defoaming the mixture for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film containing the glycerol prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing the anthocyanin prepared in the step (2) on the cellulose acetate film, and drying the cellulose acetate film for 1 hour at the temperature of 45 ℃ to obtain a composite film;

and (3) carrying out a dry compounding process on the outer layer of the polybutylene adipate/terephthalate film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

Example 7:

the preparation method of the controlled release degradable active packaging film of the embodiment comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film containing 33 wt% of glycerol: preparing an acetone aqueous solution with a mass ratio of 9:1, mixing 10g of cellulose acetate, 5g of glycerol and 90g of the acetone aqueous solution, and stirring at normal temperature until the mixture is dissolved to obtain a first mixed solution; spreading the first mixed solution on a glass plate, drying at 25 ℃ for 15min, and then removing the glass plate to obtain a cellulose acetate film containing glycerol; and then putting the cellulose acetate film into a flow channel of high-pressure water equipment to enable water flow to pass through the film for 1h, wherein the pressure intensity of water is 0.3MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol membrane liquid containing anthocyanin: weighing 4g of corn starch, mixing with 50g of water, stirring in a water bath at 95 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4g of polyvinyl alcohol (PVA) resin, mixing with 50g of water, and stirring in the water bath at 95 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding 1.2g of glycerol and 1.2g of citric acid, mixing, and stirring in a water bath at 95 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 1.2g of anthocyanin (serving as an antioxidant) into the second mixed solution, stirring the mixture in a water bath at 45 ℃ until the mixture is uniformly mixed, and then ultrasonically defoaming the mixture for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film containing the glycerol prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing the anthocyanin prepared in the step (2) on the cellulose acetate film, and drying the cellulose acetate film for 1 hour at the temperature of 45 ℃ to obtain a composite film;

and (3) carrying out a dry compounding process on the outer layer of the polybutylene adipate/terephthalate film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

Example 8:

the preparation method of the controlled release degradable active packaging film of the embodiment comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film containing 33 wt% of glycerol: preparing an acetone aqueous solution with a mass ratio of 9:1, mixing 10g of cellulose acetate, 5g of glycerol and 90g of the acetone aqueous solution, and stirring at normal temperature until the mixture is dissolved to obtain a first mixed solution; spreading the first mixed solution on a glass plate, drying at 25 ℃ for 15min, and then removing the glass plate to obtain a cellulose acetate film containing glycerol; and then putting the cellulose acetate film into a flow channel of high-pressure water equipment to enable water flow to pass through the film for 1h, wherein the pressure intensity of water is 0.5MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol membrane liquid containing anthocyanin: weighing 4g of corn starch, mixing with 50g of water, stirring in a water bath at 95 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4g of polyvinyl alcohol (PVA) resin, mixing with 50g of water, and stirring in the water bath at 95 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding 1.2g of glycerol and 1.2g of citric acid, mixing, and stirring in a water bath at 95 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 1.2g of anthocyanin (serving as an antioxidant) into the second mixed solution, stirring the mixture in a water bath at 45 ℃ until the mixture is uniformly mixed, and then ultrasonically defoaming the mixture for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film containing the glycerol prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing the anthocyanin prepared in the step (2) on the cellulose acetate film, and drying the cellulose acetate film for 1 hour at the temperature of 45 ℃ to obtain a composite film;

and (3) carrying out a dry compounding process on the outer layer of the polybutylene adipate/terephthalate film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

Example 9:

the preparation method of the controlled release degradable active packaging film of the embodiment comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film containing 33 wt% of glycerol: preparing an acetone aqueous solution with a mass ratio of 9:1, mixing 10g of cellulose acetate, 5g of glycerol and 90g of the acetone aqueous solution, and stirring at normal temperature until the mixture is dissolved to obtain a first mixed solution; spreading the first mixed solution on a glass plate, drying at 25 ℃ for 15min, and then removing the glass plate to obtain a cellulose acetate film containing glycerol; and then putting the cellulose acetate film into a flow channel of high-pressure water equipment to enable water flow to pass through the film for 1h, wherein the pressure intensity of water is 0.8MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol membrane liquid containing anthocyanin and sodium lactate: weighing 4g of corn starch, mixing with 50g of water, stirring in a water bath at 95 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4g of polyvinyl alcohol (PVA) resin, mixing with 50g of water, and stirring in the water bath at 95 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding 1.2g of glycerol and 1.2g of citric acid, mixing, and stirring in a water bath at 95 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 0.6g of sodium lactate (used as an antibacterial agent) and 0.6g of anthocyanin (used as an antioxidant) into the second mixed solution, stirring the mixture in a water bath at 45 ℃ until the mixture is uniformly mixed, and then ultrasonically defoaming the mixture for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film containing the glycerol prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing anthocyanin and sodium lactate prepared in the step (2) on the cellulose acetate film, and drying the cellulose acetate film liquid at the temperature of 45 ℃ for 1h to obtain a composite film;

and (3) carrying out a dry compounding process on the outer layer of the polybutylene adipate/terephthalate film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

Comparative example 1:

the preparation method of the controlled release degradable active packaging film of the comparative example comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film (without glycerol): preparing an acetone aqueous solution with a mass ratio of 9:1, mixing 10g of cellulose acetate and 90g of the acetone aqueous solution, and stirring at normal temperature until the cellulose acetate and the acetone aqueous solution are dissolved to obtain a first mixed solution; spreading the first mixed solution on a glass plate, drying for 15min at 25 ℃, and then removing the first mixed solution from the glass plate to obtain a cellulose acetate film; and then putting the cellulose acetate film into a flow channel of high-pressure water equipment to enable water flow to pass through the film for 1h, wherein the pressure intensity of water is 0.8MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol film liquid containing sodium lactate: weighing 4g of corn starch, mixing with 50g of water, stirring in a water bath at 95 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4g of polyvinyl alcohol (PVA) resin, mixing with 50g of water, and stirring in the water bath at 95 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding 1.2g of glycerol and 1.2g of citric acid, mixing, and stirring in a water bath at 95 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 1.2g of sodium lactate (used as an antibacterial agent) into the second mixed solution, stirring the mixture in a water bath at 45 ℃ until the mixture is uniformly mixed, and then ultrasonically defoaming the mixture for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing sodium lactate in the step (2) on the cellulose acetate film, and drying the cellulose acetate film for 1 hour at the temperature of 45 ℃ to obtain a composite film;

and (3) carrying out a dry compounding process on the outer polylactic acid film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

Comparative example 2:

the preparation method of the controlled release degradable active packaging film of the comparative example comprises the following steps:

(1) preparing an inner layer:

preparation of cellulose acetate film (without glycerol): preparing an acetone aqueous solution with a mass ratio of 9:1, mixing 10g of cellulose acetate and 90g of the acetone aqueous solution, and stirring at normal temperature until the cellulose acetate and the acetone aqueous solution are dissolved to obtain a first mixed solution; spreading the first mixed solution on a glass plate, drying for 15min at 25 ℃, and then removing the first mixed solution from the glass plate to obtain a cellulose acetate film; and then putting the cellulose acetate film into a flow channel of high-pressure water equipment to enable water flow to pass through the film for 1h, wherein the pressure intensity of water is 0.8MPa, and finally putting the film into an oven to be dried to obtain a dried film.

(2) Preparing an intermediate layer:

preparing starch/polyvinyl alcohol membrane liquid containing anthocyanin: weighing 4g of corn starch, mixing with 50g of water, stirring in a water bath at 95 ℃ until the corn starch is completely dissolved to obtain a starch solution, weighing 4g of polyvinyl alcohol (PVA) resin, mixing with 50g of water, and stirring in the water bath at 95 ℃ until the polyvinyl alcohol resin is completely dissolved to obtain a polyvinyl alcohol glue solution; adding the polyvinyl alcohol glue solution into the starch solution, adding 1.2g of glycerol and 1.2g of citric acid, mixing, and stirring in a water bath at 95 ℃ until the mixture is uniformly mixed to obtain a second mixed solution; and then cooling the second mixed solution to 45 ℃, adding 1.2g of anthocyanin (serving as an antioxidant) into the second mixed solution, stirring the mixture in a water bath at 45 ℃ until the mixture is uniformly mixed, and then ultrasonically defoaming the mixture for later use.

(3) And preparing a three-layer composite film:

spreading the cellulose acetate film prepared in the step (1) on a glass plate, clamping two ends of the glass plate by using clamps, spreading the starch/polyvinyl alcohol film liquid containing anthocyanin in the step (2) on the cellulose acetate film, and drying the cellulose acetate film liquid at the temperature of 45 ℃ for 1 hour to obtain a composite film;

and (3) carrying out a dry compounding process on the outer layer of the polybutylene adipate/terephthalate film and the composite film to obtain a three-layer composite film material, namely the controlled-release degradable active packaging film.

< experiment >

The following release performance experiments were performed using the controlled release degradable active packaging films prepared in the above examples and comparative examples as products:

the active substances (sodium lactate and anthocyanin) released from the film into the food simulant liquid are periodically measured by a release (migration) experiment with distilled water as the food simulant liquid (simulant aqueous food), fig. 1 is the change of the release amount of the sodium lactate in the film from the film into the food simulant liquid with time, and the ordinate is the ratio of the amount (Mt) of the sodium lactate in the film released into the food simulant liquid to the original sodium lactate content (Mp) in the film. Fig. 2 is a graph showing the release amount of anthocyanin in the film from the film into the food simulant as a function of time, and the ordinate is the ratio of the amount of anthocyanin in the film released into the food simulant (Mt) to the original anthocyanin content in the film (Mp). The experimental results are as follows:

as can be seen from fig. 1 and 2, the release amounts of sodium lactate and anthocyanin in the film gradually increased with time. Comparing four films of comparative example 1, example 2 and example 9, the rate of release to reach the equilibrium state is as follows: example 2 ≈ example 9 > example 1. Comparing four films of comparative example 2, example 5, example 6 and example 9, the rate of release to reach the equilibrium state is as follows: example 6 ≈ example 9 > example 5 > comparative example 2. It can be seen that the release rates of both sodium lactate and anthocyanins from the film increased with increasing glycerol content of the inner cellulose acetate film. The reason for this is that glycerin interacts with cellulose acetate to form a plasticized region inside the cellulose acetate film, and under the action of water flow having a certain pressure, a film having nanopores can be formed, and the porosity increases with the increase of the glycerin content, thereby increasing the permeability of the film and accelerating the release of the active substance. Comparing the four films of example 2, example 3, example 4 and example 9, the rate of release to reach the equilibrium state was in order: example 2 ≈ example 9 > example 4 > example 3. Comparing the four films of example 6, example 7, example 8 and example 9, the rate of release to reach the equilibrium state was in order: example 6 ≈ example 9 > example 8 > example 7. It can be seen that as the processing water pressure increases during the preparation of the cellulose acetate film, the release rates of both sodium lactate and anthocyanin in the film increase. The reason for this is that the size and porosity of the voids formed in the cellulose acetate film increase with the increase in the pressure of water flow, thereby increasing the permeability of the film and accelerating the release of the active substance. Therefore, the following conclusions can be drawn: the multi-layer composite film can control the release of active substances (sodium lactate and anthocyanin) in the film by adjusting the permeability of the inner cellulose acetate film.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. It will be readily apparent to those skilled in the art that various modifications to these embodiments and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments. Those skilled in the art should appreciate that many modifications and variations are possible in light of the above teaching without departing from the scope of the invention.