CN108211816A - A kind of resistance oxygen water permeable membrane and its preparation method and application - Google Patents

Abstract

The invention provides an oxygen barrier and water permeable film and its preparation method and application. The oxygen barrier and water permeable film includes a substrate and an oxygen barrier and water permeable layer; the oxygen barrier and water permeable layer includes alternately laminated hydrotalcite nanosheets and hydrophilic polymer layers; The substrate is in contact with the hydrotalcite nano sheet layer in the oxygen barrier and water permeable layer, and the outermost layer is a hydrophilic polymer layer. The results of the examples show that the oxygen permeation rate of the oxygen barrier and water permeable film of the present invention is 1.128～2.783 cm ³ ·m ^‑2 ·day ^‑1 ·atm ^‑1 which is lower than the oxygen permeation rate of the polypropylene film 98.143 cm ³ ·m ^‑2 ·day ^‑1 ·atm ^‑1 ; the water vapor transmission rate of the oxygen barrier and water permeable film of the present invention is 2.32cm ³ ·m ^‑2 ·day ^‑1 ·atm ^‑1 , which is higher than the water vapor transmission rate of the polypropylene film 1.95cm ³ ·m ^‑2 ·day ^‑1 ·atm ^‑1 , the oxygen barrier and water permeable film of the present invention has the performance of blocking oxygen and permeating water vapor.

Description

A kind of oxygen barrier water permeable film and its preparation method and application

technical field

The invention belongs to the technical field of membrane separation, and in particular relates to an oxygen barrier and water permeable membrane, a preparation method and application thereof.

Background technique

Organic-inorganic composite thin films have received increasing attention as gas barrier films. Organic-inorganic composite film materials have the characteristics of transparency, bendability, and good gas barrier properties, and have been widely used as ordinary sealing packaging materials. The gas barrier of organic-inorganic composite thin films in the prior art is usually based on physical barrier effect, which can only simply achieve indiscriminate gas barrier. However, in some fields, such as anaerobic wet fermentation, air dehumidification and other fields, it is required that the film must have certain water vapor regulation performance, that is, water vapor transmission performance, while having oxygen barrier performance, but there is no such thing in the prior art. There is no report of a film with oxygen barrier and water vapor permeability properties at the same time.

Contents of the invention

The invention provides an oxygen-barrier water-permeable film. The oxygen-barrier water-permeable film provided by the invention has both oxygen barrier and water vapor permeability properties.

The invention provides an oxygen barrier and water permeable film, comprising a substrate and an oxygen barrier and water permeable layer; the oxygen barrier and water permeable layer includes alternately laminated hydrotalcite nanosheet layers and hydrophilic polymer layers; the base and the oxygen barrier and water permeable layer The hydrotalcite nano-sheets are connected; the outermost layer of the oxygen barrier and water-permeable film is a hydrophilic polymer layer; the hydrotalcite nano-sheets are parallel to the substrate.

Preferably, the material of the substrate is polyethylene, polypropylene or polyethylene terephthalate, and the material of the hydrophilic polymer layer is carboxymethyl cellulose, hydroxypropyl methyl cellulose, Polyvinylpyrrolidone or polyvinyl chloride.

Preferably, the total thickness of the oxygen barrier and water permeable layer is 6-9 μm.

Preferably, the thickness of each hydrophilic polymer layer is 1-6 μm.

Preferably, the hydrotalcite nanosheets are composed of hydrotalcite nanosheets, the aspect ratio of the hydrotalcite nanosheets is 20-200; the thickness of each layer of the hydrotalcite nanosheets is 4-200 nm.

The present invention also provides a preparation method of the above-mentioned oxygen barrier and water permeable film, comprising the following steps:

(1) Provide hydrotalcite nanosheet dispersion and hydrophilic polymer dispersion;

(2) Alternate spin-coating the hydrotalcite nanosheet dispersion and the hydrophilic polymer dispersion on the substrate to obtain a composite film;

(3) Drying the composite film to obtain an oxygen barrier and water permeable film.

Preferably, the mass concentration of the hydrotalcite nanosheet dispersion is 0.1-1.0%; the mass concentration of the hydrophilic polymer dispersion is 3-5%.

Preferably, the preparation method of described hydrotalcite nanoplate comprises:

Mix M ²⁺ , M ³⁺ , urea and water to obtain a mixed solution; the M ²⁺ includes Mg ²⁺ , Zn ²⁺ or Ni ²⁺ , and the M ³⁺ includes Fe ³⁺ , Al ³⁺ or Co ³⁺ ;

performing a crystallization reaction on the mixed solution, and cooling the product of the crystallization reaction to room temperature to obtain hydrotalcite nanosheets;

The temperature of the crystallization reaction is 100-120° C., and the time of the crystallization reaction is 20-30 hours.

Preferably, the molar ratio of M ²⁺ to M ³⁺ is 2 to 4:1; the ratio of the urea to the total amount of metal ions in the mixed solution is 2 to 4:1; The concentration of urea is 0.5-1.5mol/L.

The present invention also provides the application of the above oxygen barrier and water permeable film or the oxygen barrier and water permeable film prepared by the above preparation method in separating water vapor and oxygen.

The invention provides an oxygen barrier and water permeable film, comprising a substrate and an oxygen barrier and water permeable layer; the oxygen barrier and water permeable layer includes alternately laminated hydrotalcite nanosheet layers and hydrophilic polymer layers; the base and the oxygen barrier and water permeable layer The hydrotalcite nano-sheets are connected; the outermost layer of the oxygen barrier and water-permeable film is a hydrophilic polymer layer; the hydrotalcite nano-sheets are parallel to the substrate. The oxygen-barrier and water-permeable film provided by the invention has the properties of oxygen barrier and water vapor permeability. The hydrotalcite nanosheets used in the present invention are parallel to the substrate, which greatly prolongs the path for oxygen to pass through, so that oxygen can be blocked on the outside of the film; the hydrophilic polymer can absorb a large number of water molecules, increasing the penetration of water on both sides of the substrate pressure, so that the film has water vapor permeable properties. The results of the examples show that the oxygen permeation rate of the oxygen barrier and water permeable film provided by the present invention is 1.128～2.783 cm ³ ·m ^-2 ·day ^-1 ·atm ^-1 , far lower than the oxygen permeation rate of the traditional polypropylene film of 98.143 cm ³ · m ^-2 · day ^-1 · atm ^-1 . It can be seen that the oxygen barrier and water permeable film provided by the present invention can effectively block oxygen on the outside of the film, and has a good oxygen barrier effect; at the same time, the water vapor transmission rate of the oxygen barrier and water permeable film provided by the present invention is 2.327cm ³ ·m ^{- 2} ·day ^-1 ·atm ^-1 , which is 1.944cm ³ ·m ^-2 ·day ^-1 ·atm ^-1 higher than the water vapor transmission rate of the traditional polypropylene film substrate. It can be seen that the oxygen barrier and water permeable film provided by the present invention can effectively Permeable to water vapor, has better water vapor transmission effect.

Description of drawings

Fig. 1 is the scanning electron micrograph of the hydrotalcite nanoplate that the embodiment of the present invention 1 prepares;

Figure 2 is a scanning electron microscope image of the oxygen barrier and water permeable film prepared in Example 1 of the present invention;

Fig. 3 is an atomic microscope image of the oxygen barrier and water permeable film prepared in Example 1 of the present invention;

Fig. 4 is a scanning electron microscope image of the section of the oxygen barrier and water permeable film prepared in Example 1 of the present invention;

Fig. 5 is a transmission electron microscope image of a slice of an oxygen-barrier and water-permeable film prepared in Example 1 of the present invention;

Figure 6 shows the oxygen permeability test results of the oxygen barrier and water permeable film and the base polypropylene film prepared in Examples 1-3;

Fig. 7 is the water vapor permeability test result of the oxygen-barrier water-permeable film and the base polypropylene film prepared in Example 1;

Fig. 8 is a schematic diagram of water vapor passing through the oxygen-barrier water-permeable film prepared in Examples 1-3 of the present invention;

FIG. 9 is a schematic diagram of the oxygen-barrier and water-permeable films prepared in Examples 1-3 of the present invention to block oxygen transmission.

Detailed ways

The invention provides an oxygen barrier and water permeable film, comprising a substrate and an oxygen barrier and water permeable layer; the oxygen barrier and water permeable layer includes alternately laminated hydrotalcite nanosheet layers and hydrophilic polymer layers; the base and the oxygen barrier and water permeable layer The hydrotalcite nano-sheets are connected; the outermost layer of the oxygen barrier and water-permeable film is a hydrophilic polymer layer; the hydrotalcite nano-sheets are parallel to the substrate.

In the present invention, the material of the substrate is preferably polyethylene, polypropylene or polyethylene terephthalate. The thickness of the substrate is preferably 0.2-0.3 mm, more preferably 0.25-0.3 mm.

In the present invention, the oxygen barrier and water permeable layer includes alternately laminated hydrotalcite nanosheets and hydrophilic polymer layers; the substrate is in contact with the hydrotalcite nanosheets in the oxygen barrier and water permeable layer; the oxygen barrier The outermost layer of the water-permeable film is a hydrophilic polymer layer, that is, the structure of the oxygen-blocking water-permeable film is as follows: substrate, hydrotalcite nanosheets, hydrophilic polymer layer, hydrotalcite nanosheets, ..., Hydrophilic polymer layer.

In the present invention, the hydrotalcite nanosheets and hydrophilic polymer layers are alternately laminated; the present invention uses one layer of hydrotalcite nanosheets and one hydrophilic polymer layer as a cycle unit, and the cycle unit The number of cycles is preferably 25 to 40 times, more preferably 30 to 40 times, more preferably 35 to 40 times.

In the present invention, the hydrotalcite nanosheet layer is composed of stacked hydrotalcite nanosheets, and the aspect ratio of the hydrotalcite nanosheets is preferably 20-200, more preferably 50-150, and more preferably 70-120; The thickness of the hydrotalcite nanosheet layer is preferably 4-200 nm, more preferably 50-150 mm, more preferably 70-120 mm. In the present invention, if the thickness of the hydrotalcite nanosheets is too large, the film is prone to cracks and its stability decreases; if the thickness of the hydrotalcite nanosheets is too small, the oxygen barrier and water permeability of the film will deteriorate.

In the present invention, the hydrotalcite nanosheets have a large aspect ratio, so that the hydrotalcite nanosheets greatly prolong the oxygen permeation path, thereby blocking oxygen on the outside of the oxygen barrier and water permeable film. As shown in Figure 9, oxygen molecules are blocked by the polymer layer on the outside of the film, making it difficult to pass through.

In the present invention, the material of the hydrophilic polymer layer is preferably carboxymethylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone or polyvinyl chloride. In the present invention, the thickness of the hydrophilic polymer layer is preferably 1-6 μm, more preferably 2-5 μm, more preferably 3-4 μm.

In the present invention, there is mutual attraction between the hydrophilic polymer layer and the water molecules on the outside of the film, and the hydrophilic polymer layer can absorb a large amount of water molecules inside the film, increasing the amount of water on both sides of the substrate in the film. osmotic pressure, so that the film has water vapor permeable properties. As shown in Figure 8, water molecules can enter the polymer layer of the film through the adsorption of the polymer layer, and there are gaps between the hydrotalcite nanosheets in the hydrotalcite nanosheets, so that the water molecules can pass through the hydrotalcite sheets to reach At the substrate position, with the accumulation of water molecules, the osmotic pressure on both sides of the substrate is increased, thereby allowing water molecules to pass through the substrate.

The present invention also provides a preparation method of the oxygen barrier and water permeable film described in the above technical solution, comprising the following steps:

(1) Provide hydrotalcite nanosheet dispersion and hydrophilic polymer dispersion;

(2) Alternate spin-coating the hydrotalcite nanosheet dispersion and the hydrophilic polymer dispersion on the substrate to obtain a composite film;

(3) Drying the composite film to obtain an oxygen barrier and water permeable film.

The invention provides a hydrotalcite nano sheet dispersion liquid. In the present invention, the mass concentration of the hydrotalcite nanosheet dispersion is preferably 0.1 to 1.0%, more preferably 0.2 to 0.8%, more preferably 0.4 to 0.6%; the solvent of the hydrotalcite nanosheet dispersion is preferably for deionized water. The invention mixes the hydrotalcite nanosheets with a solvent to obtain a dispersion liquid of the hydrotalcite nanosheets. In the present invention, there is no particular limitation on the mixing method, and a mixing method well known to those skilled in the art can be used.

In the present invention, the preparation method of the hydrotalcite nanosheet preferably includes:

Mix M ²⁺ , M ³⁺ , urea and water to obtain a mixed solution; the M ²⁺ includes Mg ²⁺ , Zn ²⁺ or Ni ²⁺ , and the M ³⁺ includes Fe ³⁺ , Al ³⁺ or Co ³⁺ ;

The mixed solution is subjected to a crystallization reaction, and then cooled to room temperature to obtain hydrotalcite nanosheets;

The temperature of the crystallization reaction is 100-120° C., and the time of the crystallization reaction is 20-30 hours.

The invention mixes M ²⁺ , M ³⁺ , urea and water to obtain a mixed solution. In the present invention, the M ²⁺ is preferably provided in the form of nitrate or chloride; the M ³⁺ is preferably provided in the form of nitrate or chloride. In the present invention, the M ²⁺ preferably includes Mg ²⁺ , Zn ²⁺ or Ni ^{2+ ,} and the M ³⁺ preferably includes Fe ³⁺ , Al ³⁺ or Co ³⁺ . In the present invention, the molar ratio of urea to the total amount of metal ions in the mixed solution is preferably 2 to 4:1, more preferably 2 to 3:1; M ²⁺ and M ³⁺ in the metal ions The molar ratio of is preferably 2 to 4:1, more preferably 2 to 3:1. In the present invention, the concentration of urea in the mixed solution is preferably 0.5-1.5 mol/L, more preferably 0.8-1.2 mol/L.

In the present invention, the mixing is preferably to first mix M ²⁺ , M ³⁺ and water to obtain a metal salt solution; mix urea with water to obtain a urea solution, and then mix the metal salt solution and urea solution to obtain mixture. The present invention has no special requirements on the specific implementation of the mixing, and a material mixing method well known to those skilled in the art can be used.

After the mixed solution is obtained, in the present invention, the mixed solution is preferably subjected to a crystallization reaction, and the product of the crystallization reaction is cooled to room temperature to obtain hydrotalcite nanosheets.

In the present invention, the temperature of the crystallization reaction is preferably 100-120°C, more preferably 105-115°C, and the time of the crystallization reaction is preferably 20-30h, more preferably 24-26h. In the present invention, during the crystallization process, the mixed solution gradually precipitates to generate hydrotalcite nanosheets.

In the present invention, the cooling method is preferably natural cooling.

In the present invention, after the crystallization product is cooled to room temperature, the crystallization product is preferably subjected to solid-liquid separation to obtain a solid, which is then washed and dried to obtain hydrotalcite nanosheets. The present invention has no special requirements on the method of solid-liquid separation, and the solid-liquid separation method well known to those skilled in the art can be used; in the present invention, the solid-liquid separation is further preferably centrifugal separation. When performing solid-liquid separation, the rotational speed of the centrifugal separation is preferably 1500-2000r/min, more preferably 1600-1800r/min, and the time of the centrifugal separation is preferably 5-10min, more preferably 6-8min.

In the present invention, deionized water is preferably used to wash the separated solid. The present invention has no special requirements on the amount of deionized water, as long as the solid can be submerged. In the present invention, there is no special requirement on the number of washings, and it is preferable to wash the solid until neutral; in the present invention, the number of washings is preferably 3 to 5 times. In the present invention, it is preferred to judge whether the solid is neutral by the pH value of the washing solution after washing the solid; when the pH value of the washing solution is 6.5-7.5, the solid is neutral.

Drying of the washed solids is preferred in the present invention. In the present invention, the drying temperature is preferably 50-70°C, more preferably 55-65°C; the drying time is preferably 10-15 hours, more preferably 12-14 hours. The present invention has no special requirements on the drying method, and the drying methods known to those skilled in the art can be used, preferably vacuum drying or blast drying. When vacuum drying is adopted, the pressure of the vacuum drying is preferably 0.5-0.8 atmosphere.

The present invention provides a hydrophilic polymer dispersion. In the present invention, the mass concentration of the hydrophilic polymer dispersion is preferably 3-5%, more preferably 4-5%; the solvent of the hydrophilic polymer dispersion is preferably deionized water. The present invention has no special requirements on the preparation method of the hydrophilic polymer dispersion, and the solution preparation method known to those skilled in the art can be used.

In the invention, the hydrotalcite nano sheet dispersion liquid and the hydrophilic polymer dispersion liquid are alternately spin-coated on the substrate to obtain a composite thin film.

In the present invention, the spin coating is preferably completed by a spin coater; the present invention preferably uses a vacuum method to adsorb the film substrate on the spin coater, and then the hydrotalcite nanosheet dispersion and the hydrophilic polymer water The dispersion was alternately spin-coated on the substrate. In the present invention, the first layer of spin coating is a dispersion of hydrotalcite nanosheets, and the second layer of spin coating is an aqueous dispersion of hydrophilic polymers, which are alternately spin-coated successively, and each layer of spin-coated hydrotalcite nanosheets The dispersion liquid and the aqueous dispersion liquid of the hydrophilic polymer which are spin-coated successively constitute a circulation unit, and the last layer is the aqueous dispersion liquid of the strongly hydrophilic polymer. In the present invention, the number of cycles of the circulation unit is preferably 25 to 40 times, more preferably 30 to 40 times, and even more preferably 35 to 40 times. In the present invention, when spin-coating the hydrotalcite nanosheet dispersion, the rotational speed of the spin-coating is preferably 1800-2200r/min, more preferably 2000-2200r/min; when spin-coating the hydrophilic polymer aqueous dispersion , the rotational speed of the spin coating is preferably 4500˜5500 r/min, more preferably 4800˜5200 r/min. In the present invention, the hydrotalcite nanosheets are spin-coated on the substrate through a spin coating method, so that the hydrotalcite nanosheets have an ordered orientation structure parallel to the substrate.

Before the alternate spin coating, the present invention preferably cleans the substrate. In the present invention, the cleaning preferably includes: ultrasonically cleaning the film substrate with acetone, ethanol and deionized water in sequence. In the present invention, the ultrasonic intensity of the ultrasonic cleaning is preferably 20000-30000 Hz, more preferably 24000-26000 Hz. In the present invention, the time for ultrasonic cleaning using each solvent is independently preferably 20 to 40 minutes, more preferably 25 to 35 minutes. In the present invention, there is no particular limitation on the amount of each solvent used in ultrasonic cleaning, as long as it can immerse the film substrate.

After the spin coating, the present invention dries the composite film to obtain an oxygen barrier and water permeable film. In the present invention, the drying is preferably air drying. In the present invention, the drying temperature is preferably 20-30°C, more preferably 25°C; the drying time is preferably 1-3 hours, more preferably 1.5-2.5 hours.

The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

Dissolve Mg(NO ₃ ) ₂ ·6H ₂ O and Al(NO ₃ ) ₃ ·9H ₂ O in deionized water to obtain a metal salt solution. The concentration of Mg(NO ₃ ) ₂ ·6H ₂ O in the metal salt solution is 0.4mol/L, the concentration of Al(NO ₃ ) ₃ ·9H ₂ O in the metal salt solution is 0.2mol/L; urea is dissolved in deionized water to obtain a urea solution, and the concentration of the urea solution is 0.67mol/L. 50 mL of the metal salt solution and 50 mL of the urea solution were mixed to obtain a mixed solution. Stir the mixed solution evenly, place it in an oven at 110°C, and crystallize for 24 hours, then cool the reaction system naturally to room temperature, and centrifuge to obtain a solid; wash the solid with deionized water until the deionized water after washing is medium properties, to obtain hydrotalcite nanosheets;

With deionized water as a solvent, prepare a hydrotalcite nanosheet water dispersion (abbreviated as LDH) with a mass concentration of 0.5wt.%; with deionized water as a solvent, prepare a carboxymethyl cellulose aqueous solution with a mass concentration of 4wt.%. (abbreviated as CMC);

The polypropylene film was ultrasonically cleaned with acetone, ethanol and deionized water for 30 minutes in sequence, and then rinsed with deionized water to obtain a polypropylene film substrate;

Adsorb the film substrate on a spin coating machine, spin-coat the hydrotalcite nanosheet dispersion and carboxymethyl cellulose aqueous solution successively on the surface of the film substrate, spin-coat 30 times in a cycle, and when the hydrotalcite nanosheets are dispersed Liquid, the rotating speed of spin coating is 2000r/min, when spin coating hydrophilic polymer water dispersion liquid, the rotating speed of spin coating is 5000r/min, obtains composite thin film, described composite thin film is separated from film coating machine and in Dry at 25°C to obtain an oxygen barrier and water permeable film, abbreviated as "(LDH/CMC) ₃₀ ".

Example 2

Dissolve Mg(NO ₃ ) ₂ ·6H ₂ O and Al(NO ₃ ) ₃ ·9H ₂ O in deionized water to obtain a metal salt solution. The concentration of Mg(NO ₃ ) ₂ ·6H ₂ O in the metal salt solution is 0.4mol/L, the concentration of Al(NO ₃ ) ₃ ·9H ₂ O in the metal salt solution is 0.2mol/L; urea is dissolved in deionized water to obtain a urea solution, and the concentration of the urea solution is 0.75mol/L. 50 mL of the metal salt solution and 50 mL of the urea solution were mixed to obtain a mixed solution. The mixed solution was stirred evenly, placed in an oven at 100°C, and crystallized for 26 hours, then the reaction system was naturally cooled to room temperature, and centrifuged to obtain a solid; the solid was washed with deionized water until the washed deionized water was medium properties, to obtain hydrotalcite nanosheets;

With deionized water as a solvent, prepare a hydrotalcite nanosheet water dispersion with a mass concentration of 0.1wt.%, and use deionized water as a solvent to prepare a 3wt.% hydroxypropyl methylcellulose aqueous solution (abbreviated as HPMC);

The polyethylene film was ultrasonically cleaned with acetone, ethanol and deionized water for 30 minutes in sequence, and then rinsed with deionized water to obtain a polyethylene film substrate;

Adsorb the film substrate on a spin coating machine, spin-coat the hydrotalcite nanosheet dispersion and hydroxypropyl methylcellulose aqueous solution on the surface of the film substrate successively, and spin-coat 25 times in a cycle. In the case of sheet dispersion liquid, the rotating speed of spin coating is 1800r/min, when spin coating hydrophilic polymer aqueous dispersion, the rotating speed of spin coating is 4500r/min, obtains composite film, and described composite film is separated from coating machine and dried at 25°C to obtain an oxygen barrier and water permeable film, abbreviated as "(LDH/HPMC) ₃₀ ".

Example 3

Dissolve Mg(NO ₃ ) ₂ ·6H ₂ O and Al(NO ₃ ) ₃ ·9H ₂ O in deionized water to obtain a metal salt solution. The concentration of Mg(NO ₃ ) ₂ ·6H ₂ O in the metal salt solution is 0.4mol/L, the concentration of Al(NO ₃ ) ₃ ·9H ₂ O in the metal salt solution is 0.2mol/L; urea is dissolved in deionized water to obtain a urea solution, and the concentration of the urea solution is 0.7mol/L. 50 mL of the metal salt solution and 50 mL of the urea solution were mixed to obtain a mixed solution. Stir the mixed solution evenly, place it in an oven at 110°C, and crystallize for 24 hours, then cool the reaction system naturally to room temperature, and centrifuge to obtain a solid; wash the solid with deionized water until the deionized water after washing is medium properties, to obtain large aspect ratio hydrotalcite nanosheets;

With deionized water as a solvent, prepare a water dispersion of hydrotalcite nanosheets with a large aspect ratio of 1.0wt.% in a mass concentration, and use deionized water as a solvent to prepare an aqueous solution of polyvinylpyrrolidone (abbreviated as PVP);

The polyurethane film is ultrasonically cleaned with acetone, ethanol and deionized water for 30min successively, and then rinsed with deionized water to obtain a polyurethane film substrate; When spin-coating the hydrophilic polymer aqueous dispersion, the spin-coating speed is 5500r/min;

The film base is adsorbed on a spin coating machine, the hydrotalcite nanosheet dispersion and the polyvinyl chloride aqueous solution are successively spin-coated on the surface of the film base, and the spin coating is cycled 40 times to obtain a composite film, and the composite film is obtained from Separated on a film coating machine and dried at 30°C to obtain an oxygen barrier and water permeable film, abbreviated as "(LDH/PVP) ₃₀ ".

The hydrotalcite nanosheets prepared in Example 1 were characterized using a scanning electron microscope, as shown in FIG. 1 . The measured average diameter is 641 nm, the average thickness is 29 nm, and the aspect ratio is 22.1. It can be seen from FIG. 1 that the hydrotalcite nanosheets obtained in the present invention have a two-dimensional layered structure, and the particle size distribution is uniform and has a large aspect ratio. It can be seen from FIG. 1 that the hydrotalcite nanosheets prepared by the present invention are placed in parallel to form a hydrotalcite nanosheet layer.

The oxygen-barrier and water-permeable film prepared in Example 1 was characterized using a scanning electron microscope, as shown in FIG. 2 . In Fig. 2, the color is uniform and the surface is smooth, which shows that the oxygen-barrier and water-permeable film prepared by the method of the present invention is uniform, complete, and film-forming is good.

The oxygen barrier and water permeable film prepared in Example 1 was characterized by an atomic microscope, as shown in FIG. 3 . In Fig. 3, the surface of the film is even and uniform, indicating that the oxygen barrier and water permeable film prepared by the method of the present invention is uniform, complete and well formed.

The cross-section of the oxygen-barrier and water-permeable film prepared in Example 1 was characterized by a scanning electron microscope, as shown in FIG. 4 . The darkest part in the picture is the film base, the middle part is the oxygen barrier and water permeable layer, and the lighter part is the background. It can be seen from FIG. 4 that the structure of the oxygen-barrier and water-permeable film obtained in the present invention is that the oxygen-barrier and water-permeable layer is attached to the film substrate, and in this embodiment, the thickness of the oxygen-barrier and water-permeable layer is 8 μm.

The oxygen-barrier and water-permeable film obtained in this example was sliced at -180°C, and its cross-section was characterized by a transmission electron microscope, as shown in FIG. 5 . The light-colored layer in the figure is the hydrophilic polymer layer, and the dark-colored layer is the hydrotalcite nanosheet layer. It is measured that in the film obtained in this example, the average thickness of the hydrophilic polymer layer is 204 nm, and the average thickness of the hydrotalcite nanosheet layer is 67 nm.

The oxygen barrier and water permeable films prepared in Examples 1 to 3 and the base polypropylene film were tested for oxygen permeability according to the GB/T 1038-2000 standard, and the results are shown in FIG. 6 .

From the test results in Figure 6, it can be seen that the oxygen transmission rate of the polypropylene film is 98.143cm ³ ·m ^-2 ·day ^-1 ·atm ^-1 ; while the oxygen transmission rate of the oxygen barrier and water permeable film provided by the present invention is 1.128cm ³ · m ^-2 ·day ^-1 ·atm ^-1 , 2.783 cm ³ ·m ^-2 ·day ^-1 ·atm ^-1 and 1.857 cm ³ ·m ^-2 ·day ^-1 ·atm ^-1 . The oxygen permeation rate of the oxygen barrier and water permeable film provided by the present invention is far lower than that of the polypropylene film, which shows that the oxygen barrier and water permeable film provided by the present invention can effectively block oxygen on the outside of the film, and has better Oxygen barrier effect.

The water vapor permeability test was carried out on the oxygen barrier and water permeable films prepared in Examples 1 to 3 and the base polypropylene film using the GB/T 21529-2008 standard, and the results are shown in FIG. 7 .

From the test results in Figure 7, it can be seen that the water vapor transmission rate of the polypropylene film substrate is 1.95 cm ³ ·m ⁻² ·day ⁻¹ ·atm ⁻¹ ; while the water vapor transmission rate of the oxygen barrier and water permeable film provided in Example 1 of the present invention is 2.32cm ³ ·m ^-2 ·day ^-1 ·atm ^-1 . It can be seen from the above that the oxygen barrier and water permeable film provided by the present invention can effectively permeate water vapor and has a better water vapor permeation effect.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. An oxygen barrier and water permeable film, comprising a substrate and an oxygen barrier and water permeable layer; the oxygen barrier and water permeable layer comprises alternately laminated hydrotalcite nanosheets and hydrophilic polymer layers; the base and the oxygen barrier and water permeable layer The hydrotalcite nano-sheets are connected; the outermost layer of the oxygen barrier and water-permeable film is a hydrophilic polymer layer; the hydrotalcite nano-sheets are parallel to the substrate. 2. The oxygen barrier and water permeable film according to claim 1, wherein the material of the substrate is polyethylene, polypropylene or polyethylene terephthalate; the material of the hydrophilic polymer layer It is carboxymethylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone or polyvinyl chloride. 3. The oxygen barrier and water permeable film according to claim 1 or 2, characterized in that the total thickness of the oxygen barrier and water permeable layer is 6-9 μm. 4 . The oxygen barrier and water permeable film according to claim 3 , wherein the thickness of each hydrophilic polymer layer is 1-6 μm. 5. The oxygen-blocking and water-permeable film according to claim 1 or 4, wherein the hydrotalcite nanosheets are composed of hydrotalcite nanosheets, and the aspect ratio of the hydrotalcite nanosheets is 20 to 200; The thickness of the hydrotalcite nano sheet layer is 4-200nm. 6. The preparation method of the oxygen barrier and water permeable film according to any one of claims 1 to 5, comprising the following steps: (1) Provide hydrotalcite nanosheet dispersion and hydrophilic polymer dispersion; (2) Alternate spin-coating the hydrotalcite nanosheet dispersion and the hydrophilic polymer dispersion on the substrate to obtain a composite film; (3) Drying the composite film to obtain an oxygen barrier and water permeable film. 7. The preparation method according to claim 6, characterized in that, the mass concentration of the hydrotalcite nanosheet dispersion is 0.1 to 1.0%; the mass concentration of the hydrophilic polymer dispersion is 3 to 5% . 8. according to the described preparation method of claim 6 or 7, it is characterized in that, the preparation method of described hydrotalcite nanoplate comprises: Mix M ²⁺ , M ³⁺ , urea and water to obtain a mixed solution; the M ²⁺ includes Mg ²⁺ , Zn ²⁺ or Ni ²⁺ , and the M ³⁺ includes Fe ³⁺ , Al ³⁺ or Co ³⁺ ; performing a crystallization reaction on the mixed solution, and cooling the product of the crystallization reaction to room temperature to obtain hydrotalcite nanosheets; The temperature of the crystallization reaction is 100-120° C., and the time of the crystallization reaction is 20-30 hours. 9. The preparation method according to claim 8, characterized in that, the molar ratio of M2 ⁺ to M3 ⁺ is 2 to 4:1; the amount of total substances of urea and metal ions in the mixed solution The ratio is 2-4:1; the concentration of urea in the mixed solution is 0.5-1.5 mol/L. 10. The application of the oxygen barrier and water permeable film according to any one of claims 1 to 5 or the oxygen barrier and water permeable film prepared by the preparation method according to any one of claims 6 to 9 in separating water vapor and oxygen.