CN112831121A

CN112831121A - PVDC high-barrier co-extrusion self-adhesive film for military protection and preparation method thereof

Info

Publication number: CN112831121A
Application number: CN202110146777.9A
Authority: CN
Inventors: 杨宜民
Original assignee: Luoyang Shengpeng New Material Technology Co ltd
Current assignee: Luoyang Shengpeng New Material Technology Co ltd
Priority date: 2021-02-03
Filing date: 2021-02-03
Publication date: 2021-05-25
Anticipated expiration: 2041-02-03
Also published as: CN112831121B

Abstract

The invention relates to the technical field of military protection, in particular to a PVDC high-barrier co-extruded self-adhesive film for military protection and a preparation method thereof. The co-extruded film can be used for military protection and dust prevention, and the possibility of generating static electricity and a weak magnetic field by dust is avoided; the water vapor transmission amount reaches about 1g/cm for 24h, and the moisture-proof effect is excellent; the pressure resistance stability is stronger.

Description

PVDC high-barrier co-extrusion self-adhesive film for military protection and preparation method thereof

Technical Field

The invention relates to the technical field of military protection, in particular to a PVDC high-barrier co-extruded self-adhesive film for military protection and a preparation method thereof.

Background

In the field of military protection, electronic products such as electronic equipment, electronic devices, digital devices and the like need to be protected by coating films, and a common method is to brush a layer of PET antistatic agent on the surface of an electronic protection film to form a very thin conductive layer on the surface of the film, so that the surface conductivity is improved, generated charges can be leaked as soon as possible, and the threat of static electricity is reduced, so as to prevent static electricity from being generated during operation, transportation and storage. Because static electricity can cause damage or breakdown to electronic devices, such as: the circuit is broken down after the static electricity is adhered by the ash; the discharge breakdown may cause direct damage to the integrated circuits and digital devices in the circuit board to the precision devices and the like. However, as time goes by, the antistatic agent applied on the surface may fail, and its antistatic effect is unstable.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a PVDC high-barrier co-extruded self-adhesive film for military protection and a preparation method thereof.

The technical scheme adopted by the invention for realizing the purpose is as follows: the PVDC high-barrier co-extrusion self-adhesive film for military protection consists of an outer layer, a first adhesive layer, a PVDC layer, a second adhesive layer, a secondary inner layer and an inner layer which are sequentially arranged, wherein the outer layer consists of linear low-density polyethylene, modified graphene and an additive, and the secondary inner layer consists of linear low-density polyethylene, metallocene polyethylene and the additive.

In the present invention, the thicknesses of the outer layer, the first adhesive layer, the barrier layer, the second adhesive layer, the sub-inner layer and the inner layer account for 20%, 10%, 25% and 25% of the total thickness of the sealant film, respectively.

Wherein the outer layer comprises the following raw materials in percentage by mass: 70-75% of linear low-density polyethylene, 25-30% of low-density polyethylene, 5-10% of modified graphene and 1-31% of admixture.

Preferably, the additive in the outer layer is formed by combining one or more of flame-retardant master batch, plasticizer, boron nitride, diatomite and hydrophobic silica.

The secondary inner layer comprises the following raw materials in percentage by mass: 50-70% of linear low-density polyethylene, 20-25% of low-density polyethylene and 10-25% of metallocene polyethylene, wherein the mass of the additive accounts for 1-31% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene.

Preferably, the additive in the secondary inner layer is formed by combining one or more of antistatic master batch, flame-retardant master batch, boron nitride and plasticizer.

The antistatic master batch is added into the co-extrusion film, so that the high barrier property of the PVDC film can be effectively utilized, the oxidative corrosion of oxygen and water vapor in the air to military precision equipment can be blocked, the electrostatic charge in the plastic packaging product can be effectively uniformly dispersed on the product, the dust adsorption caused by the electrostatic charge concentration can be avoided, the blocking between circuits can be changed, and the function and the service life of the military precision equipment can be influenced.

In a preferred mode, the inner layer comprises the following raw materials in percentage by mass: 50-55% of linear low-density polyethylene, 22-25% of low-density polyethylene and 23-25% of metallocene polyethylene, wherein the mass of the additive accounts for 2.5-32.5% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene.

Preferably, the additive in the inner layer is formed by combining one or more of antistatic master batch, flame-retardant master batch, boron nitride, an opening smooth auxiliary agent, aluminum oxide and a plasticizer.

In a second preferred mode, the inner layer comprises the following raw materials in percentage by mass: 45-50% of linear low-density polyethylene and 50-55% of self-adhesive master batch, and the mass of the added plasticizer and the mass of the antirust agent respectively account for 1-1.5% and 3-7.5% of the total mass of the linear low-density polyethylene and the self-adhesive master batch.

Preferably, the flame-retardant master batches are added in the secondary inner layer and the inner layer, the PVDC co-extruded film has self-extinguishing performance, and the PVDC co-extruded film added with the flame-retardant master batches has high barrier property of the PVDC co-extruded film and enables the flame-retardant grade of the PVDC co-extruded film to reach V₀And the protective clothing is suitable for military protective clothing.

A preparation method of a PVDC high-barrier co-extruded self-adhesive film for military protection comprises the following steps:

(1) heating a film blowing die and six extruders 3h before starting up, and starting up after the temperature of the die and the extruders reaches the set temperature and keeping the temperature for 0.5-1.0 h; (2) after the raw materials of the six film layers are respectively mixed uniformly, the raw materials are respectively sucked into corresponding extruders through a suction machine, the rotating speeds of the six extruders are adjusted, and when the film surfaces of the stretched films meet the quality requirements, operators measure the thickness, the width and the corona and adjust the thicknesses, the widths and the corona to the set requirements.

The military protective clothing is characterized in that a layer of air-impermeable film is added on the surface of non-woven protective clothing, the protective clothing has the functions of water resistance, air impermeability and bacterium isolation, the covering film of the existing protective clothing is generally a polyethylene film, the strength of the high-barrier co-extruded film produced by the invention is far higher than that of the polyethylene film when the high-barrier co-extruded film is applied to the protective clothing, and the high-barrier co-extruded self-adhesive film passes the third tests of GB19082-2009 and ASTMF1671 for bacterium isolation.

The high-barrier co-extruded self-adhesive film can be used for military protection and dust prevention, and avoids the possibility of generating static electricity and a weak magnetic field by dust; the water vapor transmission capacity reaches about 1g/cm and 24h, and the moisture-proof effect is excellent; due to the particularity of the use environment of military industry, the requirement on electronic equipment is strict, and particularly, under the conditions of rapid pressurization and decompression, the good circuit performance still needs to be kept.

According to the invention, the modified graphene is added in the outer layer, so that the electromagnetic shielding effect of the high-barrier co-extrusion self-adhesive film is improved; the flame-retardant master batch and the antistatic master batch are internally added but not externally coated, so that a film is subjected to a crosslinking reaction in a processing process, the flame-retardant property and the antistatic property of the film are greatly improved, and the surface impedance of the film can reach 10⁶-10¹⁰Omega, flame retardant rating up to V₀Grade, the service life is more than three months.

Drawings

FIG. 1 is a comparison of a PVDC film of the present invention with a prior art EVOH film.

Detailed Description

The invention is further illustrated below with reference to specific examples.

Example 1

The utility model provides a PVDC high resistant coextrusion self-adhesive film for war industry protection, by the skin that sets gradually, first bond line, PVDC layer, second bond line, secondary inlayer and inlayer constitute, the skin includes 70% linear low density polyethylene, 30% low density polyethylene, modified graphene is linear low density polyethylene, 5% of low density polyethylene total mass, the quality of plasticizer is linear low density polyethylene, 1% of low density polyethylene total mass, the quality of fire-retardant masterbatch is linear low density polyethylene, 30% of low density polyethylene total mass. The secondary inner layer comprises 70% of linear low-density polyethylene, 20% of low-density polyethylene and 10% of metallocene polyethylene, the mass of a plasticizer is 1% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene, and the mass of boron nitride is 15% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene. The inner layer consists of 50% of linear low density polyethylene and 50% of self-adhesive master batch, and the plasticizer is 1% of the total mass of the linear low density polyethylene and the self-adhesive master batch. Both the first and second adhesive layers are TIE.

The PVDC co-extruded film has self-extinguishing performance, and the PVDC co-extruded film added with the flame-retardant master batch not only has high barrier property of the PVDC co-extruded film, but also enables the flame-retardant grade of the PVDC co-extruded film to reach V₀And the protective device is suitable for military protection.

In the invention, the mass ratio of 1: 10, adding the graphene and the ferric nitrate into ethylene glycol, stirring to form a stable suspension, adding sodium acetate to a homogeneous phase, adding the polyethylene glycol to form a mixed solution, pouring the mixed solution into a high-pressure reaction kettle, reacting at the temperature of 150-200 ℃ for 6-10 hours, cooling, taking out, washing reactants with ethanol and distilled water for multiple times in sequence, filtering, and airing to obtain the modified graphene.

In the application, 80-90 parts of vinylidene chloride monomer, 5-15 parts of methyl acrylate monomer, 1-2 parts of plasticizer, 3-4 parts of heat stabilizer, 0.3 part of dispersant and 0.2 part of chelating agent are used for preparing PVDC resin, then the obtained PVDC resin is used for preparing PVDC layer correspondingly, and the PVDC layer is formed correspondingly with other film layers of the PVDC co-extruded film, the specific preparation process and principle of the PVDC resin are known technology, and the details are not repeated herein. In order to reduce thermal decomposition in the processing of the PVDC layer and improve aging resistance, dioctyl sebacate plasticizer and epoxy resin stabilizer are added in the preparation process of the PVDC resin, stearic acid amide is adopted as a lubricant, wherein the plasticizer, the stabilizer, the dispersant, the chelating agent and other auxiliary agents are added before the PVDC resin is processed, and the lubricant is mixed into the PVDC resin during co-extrusion to generate a PVDC core film layer. The thickness of the PVDC layer is 25-35 microns.

The antirust agent is prepared by the following preparation process:

(1) taking the mass ratio of 1-2: 3-5, adding an emulsifier into the linseed oil, and stirring in a constant-temperature water bath at 60 ℃ until the emulsifier is uniformly dispersed to prepare a mixture A; the mass of the emulsifier is 1-3% of that of the linseed oil; adding starch into a sodium hydroxide solution with the mass percent of 1%, uniformly stirring, adding a mixed solution of sodium phosphate with the mass percent of 4% and sodium hydroxide with the mass percent of 1%, uniformly stirring to obtain a mixture B, wherein the mass-to-volume ratio of the starch to the sodium hydroxide solution to the mixed solution is 1-3 g: 10mL of: 5-15 mL; adding the mixture B into the mixture A, stirring and reacting for 4-6h to obtain a mixture C, and carrying out spray freeze drying on the mixture C to obtain an antirust agent I for later use;

(2) mixing vinyl silicone oil and porous corn starch, and stirring uniformly to prepare an antirust agent II for later use;

(3) mixing the antirust agent I and the antirust agent II according to the weight ratio of 1: 1-1.5, and mixing uniformly to obtain the antirust agent.

Vinyl silicone oil and porous corn starch are mixed according to the weight ratio of 1: 3, utilize the characteristics of porous corn starch's big specific surface area, the cellular hole of porous starch granule, adsorb vinyl silicone oil and embed in starch granule, adsorb the embedding rate and can reach more than 96.7%, and self-adhesion masterbatch also can partly adsorb on the porous starch granule surface, has increased the surface area of self-adhesion masterbatch to improve the adhesive force of crowded membrane altogether, can reduce the required consumptive material of military industry equipment package. Meanwhile, when the co-extruded film is used for packaging military equipment and a bad storage and transportation environment such as film damage is caused in the storage and transportation process, the oil inside the antirust agent extends to the extruded part of the packaging film, so that the inner package is prevented from being exposed in the air, and the surface oxidation of the equipment is avoided.

The co-extrusion film has good barrier property, and has very high barrier property to oxygen, nitrogen, carbon dioxide or water vapor; its barrier properties are several times or even hundreds times higher than other materials. And along with the change of the environmental humidity, the PVDC high barrier film has no change in the barrier property, and the high barrier property can be still exerted even in high-humidity environments such as high-humidity areas and southern plum rain seasons.

Determining the production time according to the set requirements; heating the film blowing machine die set 3 hours before starting up; setting the temperature of a first zone, a second zone, a third zone and a fourth zone of the first heating die set to be 150 ℃, setting the temperature of the die to be 184 ℃ for the second time when the temperature of the die reaches 150 ℃, and continuously heating to the set temperature; simultaneously setting the temperature of each extruder for the first time and starting heating; the temperature of the first zone of the No. 1, No. 3 and No. 5 extruders is set to be 130 ℃, and the temperature of the second zone, the third zone, the fourth zone and the fifth zone are set to be 140 ℃; the temperature of a first zone of the No. 2 extruder is set to be 100 ℃, and the temperature of a second zone, a third zone, a fourth zone and a fifth zone of the No. 2 extruder is set to be 110 ℃; the first temperature zone of No. 4 and No. 6 extruders is set to be 80 ℃, and the second zone, the third zone, the fourth zone and the fifth zone are all set to be 100 ℃; when the temperatures of all the extruders reach the set temperature, setting the temperature for the second time, and setting the temperature of each extruder, wherein the first zone of the No. 1 extruder is set to be 170 ℃, the second zone is set to be 180 ℃, the third zone is set to be 185 ℃ and the fourth zone is set to be 186 ℃; the first zone of the No. 2 extruder is set to be 130 ℃, the second zone and the third zone are 140 ℃, and the fourth zone and the fifth zone are 142 ℃; the first zone of the No. 3 extruder is set to be 172 ℃, the second zone is set to be 180 ℃, the third zone and the fourth zone are set to be 185 ℃, and the fifth zone is set to be 186 ℃; the first zone of the No. 5 extruder is set to be 174 ℃, the second zone is set to be 182 ℃, the third zone and the fourth zone are set to be 184 ℃, and the fifth zone is set to be 186 ℃; the first zone of the No. 4 and No. 6 extruders is set to be 120 ℃, and the second zone, the third zone, the fourth zone and the fifth zone are set to be 130 ℃; and when the temperature of the die and the temperature of the extruder reach the set temperature, starting the extruder after heat preservation is carried out for 0.5 hour. The temperature of each extruder is adjusted in a small range according to the condition of the film surface after the extruder is started.

The raw materials are taken according to a production formula, weighed according to a formula ratio and then sequentially loaded into a mixer for mixing, wherein the mixing time is 15 minutes after all the raw materials enter the mixer, so that all the raw materials are uniformly mixed; the raw materials used by each extruder are different and are respectively mixed in sequence. The raw materials which are uniformly mixed and stirred are circulated to a film blowing machine by a stainless steel circulating basket; when the temperature of a die of a film blowing unit and the temperature of an extruder reach set values, raw materials required by each group of extruders are sucked into a hopper through a suction machine, then the rotating speed of each extruder is respectively adjusted on a central control, the rotating speeds of No. 1, No. 3 and No. 5 are adjusted to be 30Hz, No. 2 is 20 Hz, No. 4 and No. 6 are 15 Hz, when the raw materials in the extruders reach die orifices through the die, an operator draws films out of the die orifices, sequentially upwards passes through a foam stabilizer, a herringbone deck, a drawing and an upper rotating, then sequentially downwards passes through each roller, and a corona machine, a deviation corrector, a second drawing and finally reaches a winding shaft, wherein the rotating speeds of each extruder are adjusted to be respectively: numbers 1, 3 and 5 were 50 Hz, numbers 2 were 30Hz, and numbers 4 and 6 were 25 Hz; setting a first traction speed to be 10 Hz, a second traction speed to be 30Hz, external air 36, inlet air 13, outlet air 25 and winding at 11 m/min; when the film surface of the co-extrusion film meets the quality requirement, an operator measures the thickness, the width and the corona and adjusts the thickness, the width and the corona to the order requirement; in the production process, an operator performs self-inspection on the specification, the model, the appearance quality and the like of the product according to the product quality requirement; obviously marking the defective products, and remarking on the production record; after the products are produced, packaging is carried out, the products are transferred to a semi-finished product storage area and placed on a tray for later use; and covered with a black film to prevent light from directly irradiating the product.

During cutting, black spots, crystal spots and impurities generated in the production process are removed by operators; packaging the cut products in an inner package according to the packaging requirements, boxing and labeling; the product is cut and is packed the in-process detection room and sample immediately according to this batch of product quantity and detect, and the detection project is: sensory, specification and size, mechanical index, optical property, barrier property and other indexes; the boxed products are uniformly stacked on the tray according to requirements and are timely transferred to a finished product warehouse, and the inspection data of the prepared finished products are shown in the following table 1.

Table 1 inspection data for the product obtained in example 1

Example 2

A PVDC high-barrier co-extrusion self-adhesive film for military protection comprises an outer layer, a first adhesive layer, a PVDC layer, a second adhesive layer, a secondary inner layer and an inner layer which are sequentially arranged,

the outer layer consists of 75% of linear low-density polyethylene, 25% of low-density polyethylene, 7% of modified graphene, 20% of flame-retardant master batch, 1% of plasticizer, 1.5% of boron nitride, 4% of diatomite and 4% of hydrophobic silicon dioxide. The secondary inner layer consists of 55% of linear low-density polyethylene, 22% of low-density polyethylene, 23% of metallocene polyethylene, 1.5% of antistatic master batch, 2.0% of boron nitride, 22% of flame-retardant master batch and 1% of plasticizer. The inner layer consists of 50% of linear low-density polyethylene, 25% of metallocene polyethylene, 1.5% of opening slipping agent, 3% of boron nitride, 2% of aluminum oxide, 18% of antistatic master batch and 1% of plasticizer. Both the first and second adhesive layers are TIE. The addition of boron nitride enables the inner layer of the co-extruded film to have excellent friction resistance.

According to the special structure of the diatomite, boron nitride and hydrophobic silicon dioxide can be adsorbed in the pores of the diatomite and the nano pores of the diatomite and the diatomite for quality inspection, the outer layer of the co-extruded film has excellent hydrophobic performance due to the synergistic effect of the boron nitride and the hydrophobic silicon dioxide, and the outer layer of the co-extruded film has excellent friction resistance and oxidation resistance due to the synergistic effect of the boron nitride and the diatomite. The boron nitride, the aluminum oxide and the antistatic master batch are added into the inner layer, and the synergistic effect of the boron nitride, the aluminum oxide and the antistatic master batch enables the co-extrusion film to have excellent antistatic property, and meanwhile, the heat conductivity of the co-extrusion film is improved, and the heat conductivity can reach more than 1.8W/(m.K).

The finished product was prepared according to the procedure of example 1 and the test data are shown in table 2 below.

Table 2 inspection data for the product obtained in example 2

Example 3

The PVDC high-barrier co-extrusion self-adhesive film for military protection consists of an outer layer, a first adhesive layer, a PVDC layer, a second adhesive layer, a secondary inner layer and an inner layer which are sequentially arranged. The outer layer comprises 73% of linear low-density polyethylene and 22% of low-density polyethylene, the flame-retardant master batch is 17% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the modified graphene, the antistatic master batch is 13% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the modified graphene, the plasticizer is 1% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the modified graphene, and the modified graphene is 7% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the modified graphene. The secondary inner layer is composed of 52% of linear low-density polyethylene, 24% of metallocene polyethylene, antistatic master batch, flame-retardant master batch and plasticizer, the plasticizer is 1% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene, the flame-retardant master batch is 10% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene, and the antistatic master batch is 10% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene. The inner layer consists of 51 percent of linear low-density polyethylene, 25 percent of low-density polyethylene, 24 percent of metallocene polyethylene, an opening slipping agent, antistatic master batch, flame-retardant master batch and a plasticizer, wherein the plasticizer is 1 percent of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene, the flame-retardant master batch is 14 percent of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene, the antistatic master batch is 16 percent of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene, and the opening slipping agent is 1.5 percent of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene. Both the first and second adhesive layers are TIE. The finished product was prepared according to the procedure of example 1 and the test data are shown in table 3 below.

Table 3 inspection data for the product obtained in example 3

The sealing film prepared by the invention is detected according to GB/T28117-2011, the sealing film is randomly sampled by 10 rolls, and the detection result is shown in the following table 4:

TABLE 4 Co-extruded film test report of the invention

The PVDC co-extrusion film has strong intermolecular cohesion and high crystallinity, chlorine atoms in molecules have hydrophobicity, hydrogen bonds cannot be formed, oxygen molecules and water molecules are difficult to move in the PVDC molecules, and therefore the PVDC co-extrusion film has excellent oxygen resistance and water resistance, and the oxygen resistance performance is not influenced by the humidity of the surrounding environment.

The PVDC co-extruded film has self-extinguishing performance, and the PVDC co-extruded film added with the flame-retardant master batch has high barrier property of the PVDC co-extruded film, enables the flame-retardant grade of the PVDC co-extruded film to reach V0 grade, and is suitable for being used in military protective clothing. During the processing of the plastic packaging film, static charges exist on a certain part of the surface of a product, and the static charges can adsorb dust to pollute the product; the antistatic master batch is added into the PVDC co-extrusion film, so that the high barrier property of the PVDC film can be effectively utilized, the oxidation corrosion of oxygen and water vapor in air to a precise electronic element can be blocked, the electrostatic charge in a plastic packaging product can be effectively uniformly dispersed on the product, the dust adsorption caused by the electrostatic charge concentration can be avoided, the barrier between circuits can be changed, and the function and the service life of the precise electronic element can be influenced.

A comparison of the PVDC film of the present invention with the EVOH film of the prior art is shown in fig. 1. As can be seen from fig. 1, the PVDC high barrier film barrier properties do not change with changes in ambient humidity. Even in high-humidity environments such as high-humidity regions and the rainy season in the south, the high barrier property can still be exerted. The PVDC co-extrusion film has strong intermolecular cohesion and high crystallinity, chlorine atoms in molecules have hydrophobicity, hydrogen bonds cannot be formed, oxygen molecules and water molecules are difficult to move in the PVDC molecules, and therefore the PVDC co-extrusion film has excellent oxygen resistance and water resistance, and the oxygen resistance performance is not influenced by the humidity of the surrounding environment.

The above description is only an example of the present invention, and not intended to limit the scope of the present invention, and all modifications of the equivalent molecular structure, equivalent synthetic preparation process, or direct or indirect application to other related technical fields, which are made by the present invention, are included in the scope of the present invention.

Claims

1. The PVDC high-barrier co-extruded self-adhesive film for military protection is characterized in that: the composite material comprises an outer layer, a first bonding layer, a PVDC layer, a second bonding layer, a secondary inner layer and an inner layer which are sequentially arranged, wherein the outer layer comprises linear low-density polyethylene, modified graphene and an additive, and the secondary inner layer comprises linear low-density polyethylene, metallocene polyethylene and an additive.

2. The PVDC high-barrier co-extruded self-adhesive film for military protection as claimed in claim 1, wherein: the thicknesses of the outer layer, the first adhesive layer, the barrier layer, the second adhesive layer, the secondary inner layer and the inner layer account for 20%, 10%, 25% and 25% of the total thickness of the sealant film, respectively.

3. The PVDC high-barrier co-extruded self-adhesive film for military protection as claimed in claim 1, wherein: the outer layer comprises the following raw materials in percentage by mass: 70-75% of linear low-density polyethylene, 25-30% of low-density polyethylene, 5-10% of modified graphene and 1-31% of admixture.

4. The PVDC high-barrier co-extruded self-adhesive film for military protection as claimed in claim 1 or 3, wherein: the additive in the outer layer is formed by combining one or more of flame-retardant master batch, plasticizer, boron nitride, diatomite and hydrophobic silicon dioxide.

5. The PVDC high-barrier co-extruded self-adhesive film for military protection as claimed in claim 1, wherein: the secondary inner layer comprises the following raw materials in percentage by mass: 50-70% of linear low-density polyethylene, 20-25% of low-density polyethylene and 10-25% of metallocene polyethylene, wherein the mass of the additive accounts for 1-31% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene.

6. The PVDC high-barrier co-extruded self-adhesive film for military protection as claimed in claim 1 or 5, wherein: the additive in the secondary inner layer is formed by combining one or more of antistatic master batch, flame-retardant master batch, boron nitride and plasticizer.

7. The PVDC high-barrier co-extruded self-adhesive film for military protection as claimed in claim 1, wherein: the inner layer comprises the following raw materials in percentage by mass: 50-55% of linear low-density polyethylene, 22-25% of low-density polyethylene and 23-25% of metallocene polyethylene, wherein the mass of the additive accounts for 2.5-32.5% of the total mass of the linear low-density polyethylene, the low-density polyethylene and the metallocene polyethylene.

8. The PVDC high-barrier co-extruded self-adhesive film for military protection as claimed in claim 7, wherein: the additive in the inner layer is formed by combining one or more of antistatic master batch, flame-retardant master batch, boron nitride, an opening smooth auxiliary agent, aluminum oxide and a plasticizer.

9. The PVDC high-barrier co-extruded self-adhesive film for military protection as claimed in claim 1, wherein: the inner layer comprises the following raw materials in percentage by mass: 45-50% of linear low-density polyethylene and 50-55% of self-adhesive master batch, and the mass of the added plasticizer and the mass of the antirust agent respectively account for 1-1.5% and 3-7.5% of the total mass of the linear low-density polyethylene and the self-adhesive master batch.

10. The method for preparing the PVDC high-barrier co-extruded self-adhesive film for military protection as claimed in claim 1, which comprises the following steps: