CN114083862B

CN114083862B - High-interface-binding-force bidirectional-stretching polylactic acid composite film and preparation method and application thereof

Info

Publication number: CN114083862B
Application number: CN202111307290.0A
Authority: CN
Inventors: 吴腾达; 李智尧; 魏婕; 李永泉; 陈曦; 郑伟
Original assignee: Xiamen Changsu Industrial Co Ltd
Current assignee: Xiamen Changsu Industrial Co Ltd
Priority date: 2021-11-05
Filing date: 2021-11-05
Publication date: 2023-02-28
Anticipated expiration: 2041-11-05
Also published as: CN114083862A

Abstract

The invention relates to the technical field of polylactic acid films, and provides a high-interface-bonding-force two-way-stretching polylactic acid composite film, and a preparation method and application thereof, wherein the film comprises a first resin layer serving as an upper surface layer and/or a lower surface layer and a second resin layer serving as a core layer, wherein the first resin layer comprises the following raw materials: polylactic acid I, tackifier and functional master batch, wherein the levorotatory optical purity of the polylactic acid I is 85-95%. The high-interface-bonding-force two-way stretching polylactic acid composite film provided by the invention is not easy to be sticky, has high interface bonding force and printing adhesion fastness, has strong coating adhesion force, and is suitable for the fields of glue compounding, surface coating, printing, evaporation and the like.

Description

High-interface-binding-force bidirectional-stretching polylactic acid composite film and preparation method and application thereof

Technical Field

The invention relates to the technical field of polylactic acid films, in particular to a bidirectional stretching polylactic acid composite film with high interface bonding force, and a preparation method and application thereof.

Background

The biaxially oriented polylactic acid film as a novel film packaging material has mechanical and optical properties close to those of biaxially oriented polypropylene except for a specific bio-based source and a biodegradable characteristic, and is concerned by material developers. Still further, more and more developers are trying to implement composite flexible packaging applications.

Researchers find that the bidirectional stretching polylactic acid film is applied to the common composite process procedures of large-area printing, glue compounding, surface coating, vacuum evaporation and the like, and has the post-processing failure caused by poor bonding force of the surface interface of the film, such as missing printing, poor peeling strength, poor bonding force of the coating and the like.

Patent application No. CN201080014836.7, published on 2012/2/29, discloses a biaxially oriented metallized polylactic acid film with high metal adhesion and high barrier properties, in contact with metal by using an amorphous polylactic acid based polymer as a first skin layer. However, the interfacial bonding force of the polylactic acid film is limited.

The patent application with the application number of CN2019010681690.4, the publication date of which is 11/12/2019, discloses a fully biodegradable high-barrier vacuum evaporation film and a preparation method thereof, wherein the coating surface of the film is an upper layer (101), and the upper layer is composed of amorphous polylactic acid or modified polylactic acid. However, the interfacial bonding force of the polylactic acid film is limited.

The patent application with the application number of CN 201911138446.X has the publication date of 2020, 2, 11 and discloses a degradable biaxially oriented polylactic acid cigarette film and a preparation method thereof, which overcome the problems that the existing polypropylene cigarette film is not degradable and the existing degradable polylactic acid film is difficult to use in the cigarette film, the scheme is that the degradable polylactic acid cigarette film consists of three layers of A, B and C which are co-extruded and stretched, wherein the layer A comprises 80-90% of heat-seal I-type PLA, 8-15% of slipping agent and 2-5% of anti-blocking agent by mass percent, and the heat-seal I-type PLA consists of 70-80% of polylactic acid II and 20-30% of non-polylactic acid II; the layer B comprises 90-95% of crystalline PLA, 1-5% of antistatic agent, 1-2% of stiffness increasing agent and 1-5% of toughening agent; the layer C comprises 94-97% of heat-seal II type PLA, 2-3% of slipping agent and 1-3% of anti-blocking agent, wherein the heat-seal II type PLA consists of 75-85% of polylactic acid II and 15-25% of non-polylactic acid II; the preparation method comprises the steps of drying the components according to the using amount, performing melt extrusion, performing biaxial tension, performing corona treatment, rolling, aging and slitting. However, the interfacial bonding force of the polylactic acid film is limited.

At present, the research on the bidirectional stretching polylactic acid film with high interface bonding force in the market is less. The application of the two-way stretching polylactic acid film in vacuum evaporation and surface layer barrier liquid coating is explained in the patent, few researches on the design of interface bonding layer material selection are carried out, and meanwhile, application researches on glue compounding, surface layer coating and the like are not carried out. The biaxially oriented composite film with high interface bonding force can solve the problem of pain points in downstream application and better promote the application of biaxially oriented polylactic acid films.

Disclosure of Invention

In order to solve the problem of limited interfacial bonding force of the polylactic acid film in the prior art, the invention provides a bidirectional stretching polylactic acid composite film with high interfacial bonding force, which comprises a first resin layer as an upper surface layer and/or a lower surface layer and a second resin layer as a core layer, wherein the first resin layer comprises the following raw materials: polylactic acid I, a tackifier and a functional master batch, wherein the levorotatory optical purity of the polylactic acid I is 85% -95%. The L-optical purity of polylactic acid corresponds to the melting point, and can be used as a comparison of the crystallization ability of polylactic acid. The higher the levorotatory optical purity of polylactic acid, the higher the crystallization ability of polylactic acid, and the higher the corresponding melting point.

In a preferred embodiment, the melting point of the polylactic acid I is 100-150 ℃ or no melting point. Polylactic acid I having a levorotatory optical purity and a melting point within the ranges disclosed in the examples of the present invention corresponds to polylactic acid having a constant crystallinity and average molecular weight, and when the crystallinity and average molecular weight are too low, the surface of a resin layer formed of the polylactic acid becomes sticky, and the film-forming property becomes poor, which is disadvantageous in processing. When the crystallinity and the average molecular weight are too high, the interface bonding force of the resin layer is easily reduced because a perfect and compact crystal region is formed on the surface of the resin.

The melting point is tested by DSC analysis, firstly heating a resin sample at 120 ℃ for 10 hours, taking 2-8 g of the sample to place in a crucible, heating from 20 ℃ to 200 ℃ at a heating rate of 10 ℃/min under the nitrogen atmosphere, and recording the peak value of the observed melting endothermic peak as the corresponding melting point.

In one embodiment, the polylactic acid I is 50-79 parts by mass, the tackifier is 15-40 parts by mass, and the functional master batch is 1-6 parts by mass.

In one embodiment, the second resin layer is made of polylactic acid II, and the levorotatory optical purity of the polylactic acid II is 95% to 100%.

In a preferred embodiment, the second resin layer only contains polylactic acid II.

In one embodiment, the thickness of the first resin layer is greater than or equal to 1 μm and less than or equal to 3 μm, and the ratio of the thickness of the first resin layer to the thickness of the second resin layer is greater than 0 and less than or equal to 0.2.

In one embodiment, the tackifier is one or more of polyethylene glycol, n-butyl citrate, polycaprolactone and polyvinyl acetate.

In one embodiment, the functional master batch comprises a slipping agent, an anti-bonding agent, an antistatic agent and polylactic resin.

In one embodiment, the content of the anti-adhesive agent in the first resin layer is 500-3000 ppm.

In one embodiment, the content of the slipping agent in the first resin layer is 1000 to 2500ppm.

In one embodiment, the anti-bonding agent is one or more of talcum powder, silicon dioxide, polymethyl methacrylate microspheres and polystyrene microspheres.

In a preferred embodiment, the median distribution size of the anti-caking agent particles is 2 to 6 μm.

In one embodiment, the slip agent is one or more of erucamide, silicone, PE wax, ethylene bis stearamide.

In one embodiment, the antistatic agent is one or more of ethoxyamine and oleamide.

In one embodiment, the composite material further comprises a third resin layer, when the first resin layer is an upper surface layer or a lower surface layer, the third resin layer is a lower surface layer or an upper surface layer, and the third resin layer contains polylactic acid III.

In a preferred embodiment, the third resin layer contains only polylactic acid III.

In a preferred embodiment, the optical purity of the poly (lactic acid III) is the same as that of a commercially available poly (lactic acid), poly (lactic acid I) or poly (lactic acid II).

The invention also provides a preparation method of the bidirectional stretching polylactic acid composite film with high interface bonding force according to any one of the technical schemes, which comprises the following steps:

fully drying the raw materials for synthesizing the upper and lower surface layers, putting the raw materials into an auxiliary extruder, fully drying the raw materials for synthesizing the core layer, putting the raw materials into a main extruder, and heating and melting the raw materials;

merging the melts in the auxiliary extruder and the main extruder in a three-layer T-shaped die head, extruding to obtain a mixed melt, and pasting the extruded mixed melt on the surface of a chill roll through an air knife to form a cast sheet;

longitudinally preheating the cast sheet, longitudinally stretching, transversely preheating in a longitudinal stretching and shaping area, transversely stretching in a transverse stretching and shaping area, corona treating, rolling, curing and cutting to obtain the biaxially oriented polylactic acid composite film with high interface bonding force.

In one embodiment of the manufacturing process, the feedstock moisture needs to be dried to less than 200 ppm.

In one embodiment of the method of preparation, the heat-melting temperature is 170 to 190 ℃.

In one embodiment of the method of manufacture, the T-die has a temperature of 195 to 200 ℃.

In an embodiment of the method of making, the chill roll has a temperature of 28 to 33 ℃.

In one embodiment of the preparation method, the longitudinal preheating temperature is 61-62 ℃, the longitudinal stretching magnification is 3.0-3.2 times, and the longitudinal stretching shaping zone temperature is 49-51 ℃.

In a preferred embodiment of the method, the temperature of the longitudinal stretch-setting zone is 50 ℃.

In an embodiment of the preparation method, the temperature of the transverse preheating is 80-82 ℃, the magnification of the transverse stretching is 3.7-4.0 times, and the temperature of the transverse stretching and shaping zone is 115-120 ℃.

In a preferred embodiment of the manufacturing method, the corona treatment layer is the first resin layer.

The invention also provides application of the high-interface-bonding-force bidirectional-stretching polylactic acid composite film in the fields of glue compounding, surface coating, printing, evaporation and the like.

Based on the above, compared with the prior art, the high-interface-bonding-force biaxially-oriented polylactic acid composite film provided by the invention is not easy to be sticky, has high interface bonding force and printing adhesion fastness, and strong coating adhesion, and is suitable for the fields of glue compounding, surface coating, printing, evaporation and the like.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts; in the following description, the drawings are illustrated in a schematic view, and the drawings are not intended to limit the present invention.

FIG. 1 is a first schematic view of a biaxially oriented polylactic acid composite film with high interfacial bonding force according to the present invention;

fig. 2 is a second schematic diagram of the biaxially oriented polylactic acid composite film with high interface bonding force provided by the invention.

Reference numerals are as follows:

100. first resin layer 200 second resin layer 300 third resin layer

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments; the technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs, and should not be construed as limiting the present invention; it will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The invention provides the following examples and comparative examples:

example 1

(1) Preparing a functional master batch:

3 parts of erucamide, 5 parts of silicon dioxide (the median size of particle size distribution is 4 mu m), 1 part of ethoxyamine and 91 parts of polylactic acid are extruded and granulated at 165-170 ℃ by a double-screw extruder to obtain the product for later use;

(2) Preparing the bidirectional stretched polylactic acid composite film with high interface bonding force:

referring to fig. 1, a schematic structural view of a biaxially oriented polylactic acid composite film with high interfacial bonding force disclosed in embodiment 1 of the present invention includes three layers sequentially arranged, wherein the first resin layer, the second resin layer and the first resin layer are sequentially arranged from top to bottom;

the components of the first resin layer comprise 78 parts of polylactic acid I (with the left-handed optical purity of 93 percent and the melting point of 145 ℃), 18 parts of polyethylene glycol 2000 and 4 parts of functional master batch in parts by weight;

the second resin layer comprises 100 parts by weight of polylactic acid II.

Wherein the thickness of the first resin layer is 2 μm, and the thickness of the second resin layer is 11 μm;

the preparation method of the bidirectional stretched polylactic acid composite film with high interface bonding force comprises the following steps:

fully drying the raw materials to below 200ppm, putting the components of the first resin layer into an auxiliary extruder, putting the components of the second resin layer into a main extruder, and heating and melting at 170-190 ℃;

converging the melts of the auxiliary extruder and the main extruder in a three-layer T-shaped die head, and then extruding to obtain a mixed melt, wherein the temperature of the three-layer T-shaped die head is 200 ℃;

applying the extruded mixed melt on the surface of a chill roll through an air knife to form a cast sheet, wherein the temperature of the chill roll is 33 ℃;

longitudinally preheating the cast sheet at 62 ℃, longitudinally stretching the cast sheet at a longitudinal stretching ratio of 3.0 times and a longitudinal stretching temperature of 65 ℃, and then entering a longitudinal stretching and shaping zone at 50 ℃;

transversely preheating the longitudinally stretched sheet at 82 ℃, transversely stretching the sheet at a transverse stretching ratio of 4 times and a transverse stretching temperature of 84 ℃, and then entering a transverse stretching and shaping zone at 120 ℃;

and carrying out corona treatment, rolling, curing and slitting on the film subjected to heat setting to obtain the bidirectional stretched polylactic acid composite film with high interface bonding force.

Example 2

(1) Preparing a functional master batch:

4 parts of ethylene bis stearamide, 3 parts of polymethyl methacrylate microspheres (the median size in particle size distribution is 3.5 mu m), 1 part of ethoxyamine and 92 parts of polylactic acid are extruded and granulated at 165-170 ℃ by a double-screw extruder to obtain the polyethylene glycol-ethylene bis stearamide-polylactic acid composite material for later use;

(2) Preparing a bidirectional stretched polylactic acid composite film with high interface bonding force:

referring to fig. 2, a schematic structural view of a biaxially oriented polylactic acid film with high interfacial bonding force disclosed in embodiment 1 of the present invention includes three layers arranged in sequence, wherein the three layers are a first resin layer, a second resin layer and a third resin layer from top to bottom;

the components of the first resin layer are, by weight, 66 parts of polylactic acid I (with a left-handed optical purity of 88% and a melting point of 115 ℃), 30 parts of polyvinyl acetate and 4 parts of functional master batch;

the components of the second resin layer are 100 parts of polylactic acid II;

the third resin layer comprises 98 parts of polylactic acid III and 2 parts of functional master batch in parts by weight;

wherein the thickness of the first resin layer is 1.5 μm, the thickness of the second resin layer is 21 μm, and the thickness of the third resin layer is 2.5 μm;

fully drying the raw materials to be less than 200ppm, putting the components of the first resin layer and the third resin layer into respective auxiliary extruders, putting the components of the second resin layer into a main extruder, and heating and melting at 170-190 ℃;

converging the melts of the auxiliary extruder and the main extruder in a three-layer T-shaped die head, and then extruding to obtain a mixed melt, wherein the temperature of the three-layer T-shaped die head is 195 ℃;

applying the extruded mixed melt on the surface of a chill roll through an air knife to form a cast sheet, wherein the temperature of the chill roll is 28 ℃;

longitudinally preheating the cast sheet at 61 ℃, longitudinally stretching the cast sheet at the longitudinal stretching ratio of 3.2 times and the longitudinal stretching temperature of 62 ℃, and then entering a 50 ℃ longitudinal stretching and shaping area;

transversely preheating the longitudinally stretched sheet at 80 ℃, transversely stretching the sheet at the transverse stretching ratio of 3.7 times and the transverse stretching temperature of 82 ℃, and then entering a transverse stretching and shaping zone at 115 ℃;

and carrying out corona treatment, rolling, curing and slitting on the film subjected to heat setting to obtain the bidirectional stretched polylactic acid composite film with high interface bonding force (the corona treatment surface is the first resin layer).

Comparative example 1

Comparative example 1 is different from example 1 only in the components used for the first resin layer, and the remaining components, preparation method and film thickness are the same; the components of the first resin layer are 78 parts of polylactic acid II (with the left-handed optical purity of 98 percent and the melting point of 163 ℃) 18 parts of polyethylene glycol 2000 and 4 parts of functional master batch in parts by weight;

comparative example 2

Comparative example 2 is different from example 1 only in the components used for the first resin layer, and the remaining components, preparation method and film thickness are the same; the components of the first resin layer are 96 parts of polylactic acid I (with the left-handed optical purity of 93 percent and the melting point of 145 ℃) and 4 parts of functional master batch in parts by weight.

Comparative example 3

Comparative example 3 is different from example 2 only in the components used for the first resin layer, and the remaining components, preparation method and film thickness are the same; the components of the first resin layer comprise, by weight, 51 parts of polylactic acid I (with the left-handed optical purity of 88% and the melting point of 115 ℃), 45 parts of polyvinyl acetate and 4 parts of functional master batch;

comparative example 4

Comparative example 4 is different from example 2 only in the components used for the first resin layer, and the remaining components, preparation method and film thickness are the same; the components of the first resin layer comprise, by weight, 62 parts of polylactic acid I (with the left-handed optical purity of 88% and the melting point of 115 ℃), 30 parts of polyvinyl acetate and 8 parts of functional master batch;

comparative example 5

Comparative example 5 is different from example 2 in the thickness of the first resin layer, and the remaining components, preparation method and film thickness are the same; the thickness of the first resin layer was 3.5 μm, the thickness of the second resin layer was 21 μm, and the thickness of the third resin layer was 2.5 μm.

Comparative example 6

Comparative example 6 is different from example 1 only in the kind of polylactic acid used for the first resin layer, and the remaining components, preparation method and film thickness are the same. The L-optical purity of the polylactic acid is 78%, and the polylactic acid has no melting point.

Comparative example 7

Comparative example 7 is different from example 1 only in the kind of polylactic acid used for the second resin layer, and the remaining components, preparation method and film thickness are the same. The L-optical purity of the polylactic acid is 92%, and the melting point of the polylactic acid is 140 ℃.

The grade and other technical indexes of the raw materials adopted in the preparation method, the examples and the comparative examples can be selected according to the prior art, and if the technical indexes are specified in the invention, the technical indexes are selected within the range specified in the invention, so that the technical effect of the invention is not influenced.

The test method adopted by the invention is as follows:

1. peel Strength test

And compounding the corona surface and the corona surface by using water-based acrylic glue, wherein the glue layer thickness is 3 mu m, and carrying out T-shaped peel strength test according to GB 8808.

2. Test of print adhesion fastness

The corona side was gravure white ink printed and tested for liquid ink adhesion according to GB/T13217.7.

3. Coating adhesion test

The corona side was coated according to the method disclosed in CN 108340670A and adhesion tested according to GB 9286.

4. Tensile Strength test of films

The tensile strength of the films was tested according to GB/T1040.3.

5. Coefficient of static/dynamic friction

The static and dynamic friction coefficient of the treated surface/non-treated surface is carried out according to GB 10006-88.

The results of testing the biaxially oriented polylactic acid composite films with high interfacial bonding force prepared in the above examples and comparative examples are shown in the following table:

TABLE 1 test results of examples and comparative examples

Note that A represents a first resin layer, B represents a second resin layer, and C represents a third resin layer

TABLE 1 test results of examples and comparative examples

The examples 1-2 have better overall properties than the comparative examples. Compared with the comparative example 1, the peel strength, the printing adhesion fastness and the coating adhesion are all stronger than those of the comparative example 1, which shows that the polylactic acid I (with the crystallinity lower than that of the polylactic acid II adopted in the comparative example 1) adopted by the first resin layer is used for reducing the crystallinity to form an irregular interface on the surface layer of the film, so that the high interface bonding force is promoted to be improved, and further, the peel strength, the printing adhesion fastness and the coating adhesion are improved; the comparison between example 1 and comparative example 2 shows that the first resin layer, if lacking tackifier, causes the surface tension to be reduced, and further causes the peeling strength, printing adhesion fastness and coating adhesion to be reduced, which is stronger than that of comparative example 2.

Example 2 compared to comparative example 3, comparative example 3 added too much tackifier, which resulted in the first resin layer being tacky and the static/dynamic coefficient of friction not being measurable, which was detrimental to subsequent processing applications of the film. Example 2 compared to comparative example 4, the smoothness of the film surface was improved due to the addition of too much functional masterbatch in comparative example 4, resulting in a decrease in peel strength, print adhesion, and coating adhesion. Example 2 compared to comparative example 5, the first resin layer of comparative example 5 is slightly tacky due to its excessive thickness, which is detrimental to the subsequent processing applications of the film. In example 1, compared with comparative example 6, since the crystallinity of the polylactic acid resin used in the first resin layer is smaller than that of polylactic acid I, the surface layer of the film is easily tacky and is not favorable for subsequent processing, and the strength of the film is reduced. Example 1 compared with comparative example 7, since the second resin layer employs polylactic acid I, the resin crystallinity is low, the film after stretching orientation has poor stretching performance, and a larger shrinkage rate is generated, resulting in a decrease in peel strength and print adhesion. It should be noted that, since polylactic acid is a semicrystalline material, the crystallization ability is related to the levorotatory purity. Low levorotatory optical purity corresponds to poor crystallization ability, and the melting point is reduced until no melting point is present. When the levorotatory optical purity is low, the mechanical properties and processability of the material are poor.

In conclusion, compared with the prior art, the high-interface-bonding-force two-way stretching polylactic acid composite film provided by the invention is not easy to be sticky, has high interface bonding force and printing adhesion fastness and strong coating adhesion, and is suitable for the fields of glue compounding, surface coating, printing, evaporation and the like.

In addition, it will be appreciated by those skilled in the art that, although there may be many problems with the prior art, each embodiment or aspect of the present invention may be improved only in one or several respects, without necessarily simultaneously solving all the technical problems listed in the prior art or in the background. It will be understood by those skilled in the art that nothing in a claim should be taken as a limitation on that claim.

Although terms such as upper surface layer, lower surface layer, first resin layer, second resin layer, polylactic acid I, polylactic acid II, polylactic acid III, tackifier, and functional master batch are used more herein, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any one or more of the appended limitations; the terms "first," "second," and the like in the description and in the claims, and in the foregoing description and in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and these modifications or substitutions do not depart from the spirit of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A bidirectional stretching polylactic acid composite film with high interface bonding force is characterized in that:

comprising a first resin layer as an upper surface layer and/or a lower surface layer and a second resin layer as a core layer, wherein,

the first resin layer comprises the following raw materials: polylactic acid I, a tackifier and a functional master batch,

-95% of the polylactic acid I having a levorotatory optical purity of 85% -95%;

-50-79 parts of the polylactic acid I, 15-40 parts of the viscosity enhancing agent, 1-6 parts of functional masterbatch, by mass;

the second resin layer is made of polylactic acid II, and the levorotatory optical purity of the polylactic acid II is 95-100%;

the thickness of the first resin layer is greater than or equal to 1 μm and less than or equal to 3 μm, and the ratio of the thickness of the first resin layer to the thickness of the second resin layer is greater than 0 and less than or equal to 0.2;

the tackifier is one or more of polyethylene glycol, n-butyl citrate, polycaprolactone and polyvinyl acetate.

2. The biaxially oriented polylactic acid composite film with high interfacial bonding force according to claim 1, wherein: the functional master batch comprises a slipping agent, an anti-bonding agent, an antistatic agent and polylactic resin.

3. The biaxially oriented polylactic acid composite film with high interfacial bonding force according to claim 2, wherein: the anti-adhesive is present in the first resin layer in an amount of 500-3000 ppm, and the slip agent is present in the first resin layer in an amount of 1000-2500 ppm.

4. The biaxially oriented polylactic acid composite film with high interfacial bonding force according to claim 2, wherein: the anti-caking agent is one or more of talcum powder, silicon dioxide, polymethyl methacrylate microspheres and polystyrene microspheres; the slipping agent is one or more of erucamide, silicone, PE wax and ethylene bis stearamide; the antistatic agent is one or more of ethoxyamine and oleamide.

5. A method for preparing the biaxially oriented polylactic acid composite film with high interfacial bonding force according to any one of claims 1 to 4, wherein the method comprises the following steps:

the method comprises the following specific steps:

6. The application of the high interfacial bonding force biaxially oriented polylactic acid composite film according to any one of claims 1 to 4 in the fields of glue compounding, surface coating, printing and evaporation.