Water-blocking film and preparation method thereof

Abstract

The invention relates to the technical field of films, and particularly provides a water-blocking film and a preparation method thereof. The water-blocking film is a film prepared from two-dimensional nano material modified PVA (Polyvinyl Alcohol). The invention aims to solve the problem that in the prior art, polyvinyl alcohol is poor in water-blocking performance, and particularly, swelling and falling off easily occur in a humid environment, so that the barrier performance is reduced. Therefore, according to the water-blocking film and the preparation method provided by the invention, the film is prepared by modifying PVA with a two-dimensional nano material, and the film has excellent water-blocking and oxygen-blocking properties, also has excellent wear resistance and mechanical properties, and is suitable for occasions needing to bear tensile stress.

Description

Technical Field

[0001] The present invention relates to the technical field of thin films, and specifically provides a water-blocking thin film and a preparation method thereof. Background Art

[0002] In recent years, the research and development of high-barrier materials has become a hot topic in the field of plastic packaging materials. Such materials have high barrier properties against oxygen, water vapor, carbon dioxide, etc., making them moisture-proof, color-preserving, and fragrance-preserving, and thus can well meet the needs of various special plastic packaging materials.

[0003] Plastic packaging materials are closely related to human life from industrial products to the living field, and are the fastest-growing and most widely used variety in the field of plastic products. With the progress and development of society, high efficiency, energy conservation, and environmental protection have become the development trend of plastic packaging materials. However, the currently used high-barrier plastics are mainly polyvinyl alcohol-based, polyvinylidene chloride-based (PVDC), and nylon-based (PA). The common characteristics of these plastics are: few varieties, high prices, narrow processing windows, and non-degradable after use, which have hindered the widespread use of plastic packaging materials.

[0004] Polyvinyl alcohol (PVA) is a water-soluble high molecular polymer with a quite wide range of uses. It is the only vinyl polymer that can be used by bacteria as a carbon source and energy source. Under the action of bacteria and enzymes, 75% can be degraded in 46 days, belonging to a biodegradable high molecular material. It can be mass-produced by a non-petroleum route and has a low price. Its oil resistance, solvent resistance, and gas barrier properties are outstanding, and it has unique advantages in food and drug packaging. However, due to the presence of a large number of hydroxyl groups in its molecular structure, the molecular chains are arranged closely, resulting in excellent barrier properties, especially the barrier property against gases such as oxygen is even better than that of polyvinylidene chloride. However, due to the hydrophilicity of the hydroxyl groups, it has strong water absorption, resulting in poor water-blocking performance of polyvinyl alcohol. Especially in a humid environment, it is prone to swelling and peeling, thus reducing the barrier performance, which greatly limits its application.

[0005] Correspondingly, the field needs a new technical solution to solve the above technical problems. Summary of the Invention

[0006] The present invention aims to solve the above technical problems, that is, to solve the problem that the water-blocking performance of polyvinyl alcohol in the prior art is poor, especially in a humid environment, it is prone to swelling and peeling, thus reducing the barrier performance.

[0007] In a first aspect, the present invention provides a water-blocking thin film, wherein the water-blocking thin film is a thin film prepared by modifying PVA with two-dimensional nanomaterials.

[0008] In a second aspect, the present invention provides a preparation method of the above water-blocking thin film, and the preparation method includes:

[0009] Provide solution A of two-dimensional nanomaterials;

[0010] Provide solution B of two-dimensional nanomaterial-modified PVA;

[0011] Prepare solution B into a film.

[0012] In a preferred technical solution of the above preparation method, solution B is provided by the following method:

[0013] First, filter solution A of two-dimensional nanomaterials, then add PVA to the filtered solution A of two-dimensional nanomaterials, heat to a preset temperature, stir at a preset speed for a preset time, and cool to room temperature to obtain solution B.

[0014] In a preferred technical solution of the above preparation method, the mass-volume ratio of PVA to solution A is (1-5) g: 20 mL in terms of g:mL;

[0015] And / or, the preset temperature is 80-100 °C;

[0016] And / or, the preset time is 4-8 h.

[0017] In a preferred technical solution of the above preparation method, the preset speed is 100-300 rpm.

[0018] In a preferred technical solution of the above preparation method, solution A of two-dimensional nanomaterials is provided by the following method:

[0019] In the presence of an organic solvent, react melamine and trimesoyl chloride under stirring to obtain solution A of the two-dimensional nanomaterials.

[0020] In a preferred technical solution of the above preparation method, the molar ratio of melamine to trimesoyl chloride is (1-4):1.

[0021] In a preferred technical solution of the above preparation method, the organic solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide, tetrahydrofuran or N-methylpyrrolidone.

[0022] In a preferred technical solution of the above preparation method, the stirring speed is 1000-3000 rpm.

[0023] In a preferred technical solution of the above preparation method, the reaction time is 2-4 h.

[0024] The water-blocking film and preparation method of the present invention have the following technical effects:

[0025] The film prepared by modifying PVA with two-dimensional nanomaterials in the present invention has excellent water and oxygen barrier properties, and also has excellent wear resistance and mechanical properties, making it suitable for applications that need to withstand tensile stress. Detailed Embodiments

[0026] The following describes the preferred embodiments of the present invention. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0027] In this application, the term "and / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Here, A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0028] In this application, "at least one" means one or more, and "a plurality" means two or more. "At least one of the following" or its similar expressions refer to any combination of these items, including any combination of single item(s) or plural item(s). For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0029] It should be understood that in various embodiments of this application, the magnitudes of the sequence numbers of the above processes do not mean the order of execution. Some or all steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0030] The terms used in the embodiments of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms "a", "the", and "said" used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0031] The weights of the relevant components mentioned in the specification of the embodiments of this application not only can refer to the specific contents of each component, but also can represent the weight ratio relationship between the components. Therefore, as long as the contents of the relevant components in the specification of the embodiments of this application are scaled up or down in proportion, they are within the scope disclosed in the specification of the embodiments of this application. Specifically, the mass described in the specification of the embodiments of this application can be mass units well-known in the chemical field such as μg, mg, g, kg, etc.

[0032] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0033] The experimental methods in the following embodiments are all conventional methods unless otherwise specified, and the materials, reagents, etc. used in the following embodiments can all be obtained from commercial channels unless otherwise specified.

[0034] Based on the problem pointed out in the background technology that the water barrier performance of polyvinyl alcohol in the prior art is poor, especially it is prone to swelling and shedding in a humid environment, thus reducing the barrier performance. The present invention provides a water barrier film and a preparation method thereof. A film is prepared by modifying PVA with two-dimensional nanomaterials. This film has excellent water barrier and oxygen barrier properties, and at the same time also has excellent wear resistance and mechanical properties.

[0035] Specifically, in the first aspect of the present invention, a water barrier film is provided, wherein the water barrier film is a film prepared by modifying PVA with two-dimensional nanomaterials.

[0036] Due to the hydrophilicity of the hydroxyl group, polyvinyl alcohol (PVA) has strong water absorption, resulting in poor water barrier performance of polyvinyl alcohol. Especially in a humid environment, it is prone to swelling and shedding, thus reducing the barrier performance, which greatly limits its application. Two-dimensional nanomaterials have excellent barrier properties, but due to their nanoscale nature, it is difficult to use them alone, and their functions cannot be fully exerted when used alone. The present invention uses PVA as the carrier material for two-dimensional nanomaterials, and the film formed by the two has excellent water barrier and oxygen barrier properties, and at the same time also has excellent wear resistance and mechanical properties.

[0037] In the second aspect of the present invention, a preparation method of the above-mentioned water barrier film is provided, and the preparation method includes:

[0038] Providing solution A of two-dimensional nanomaterials;

[0039] Providing solution B of two-dimensional nanomaterial-modified PVA;

[0040] Preparing solution B into a film.

[0041] In the present invention, a two-dimensional nanomaterial is first prepared. This material not only has a quite advanced water and oxygen barrier ability but also extremely high mechanical properties. Subsequently, the hydroxyl groups of PVA are reacted with the amino residues on the two-dimensional nanomaterial to connect the two-dimensional materials and form a three-dimensional film stacked by layers of two-dimensional materials. This film not only has water resistance, oxygen resistance, wear resistance, and antioxidant properties but also excellent mechanical properties.

[0042] In some specific embodiments, the solution B is provided by the following method:

[0043] First, filter the solution A of the two-dimensional nanomaterial, then add PVA to the filtered solution A of the two-dimensional nanomaterial, heat it to a preset temperature, stir at a preset speed for a preset time, and cool it to room temperature to obtain the solution B.

[0044] In the present invention, during the preparation process of the two-dimensional nanomaterial, to ensure that the acyl chloride groups of trimesoyl chloride fully participate in the reaction, melamine is added in excess. To avoid the reaction of these melamines with the subsequently added PVA, the solution A of the two-dimensional nanomaterial is filtered first to filter out the unreacted melamine.

[0045] In some specific embodiments, the mass-volume ratio of the PVA to the solution A is (1 - 5) g:20 mL in terms of g:mL.

[0046] In some specific embodiments, the preset temperature is 80 - 100 °C. For example, it can be 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, or any value within the range.

[0047] In some specific embodiments, the preset speed is 100 - 300 rpm. For example, it can be 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, or any value within the range.

[0048] In the present invention, stirring at the above preset speed can be achieved by mechanical stirring.

[0049] In some specific embodiments, the preset time is 4 - 8 h. For example, it can be 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, or any value within the range.

[0050] In some specific embodiments, the solution A of the two-dimensional nanomaterial is provided by the following method:

[0051] In the presence of an organic solvent, react melamine and trimesoyl chloride under stirring to obtain the solution A of the two-dimensional nanomaterial.

[0052] In the present invention, melamine and trimesoyl chloride are used as raw materials, and the two react to obtain a two-dimensional nanomaterial, thereby obtaining solution A of the two-dimensional nanomaterial. The reaction that occurs is as follows:

[0053] In the present invention, melamine and trimesoyl chloride are used as raw materials, and the two react to obtain a two-dimensional nanomaterial, thereby obtaining solution A of the two-dimensional nanomaterial. PVA is added to the filtered solution A of the two-dimensional nanomaterial, the temperature is raised to a preset temperature, and stirring is carried out at a preset speed for a preset time, and then the temperature is lowered to room temperature to obtain solution B. Under acidic conditions, the amino group of melamine and the hydroxyl group of polyvinyl alcohol undergo a condensation reaction to form a crosslinked structure. The reaction that occurs is as follows: [-CH2-CH(OH)-] n + n C3N3(NH2)3→[-CH2-CH(O-C3N3(NH)-] n + n H2O

[0054] In some specific embodiments, the molar ratio of melamine to trimesoyl chloride is (1 to 4):1.

[0055] In some specific embodiments, the organic solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide, tetrahydrofuran, or N-methylpyrrolidone.

[0056] In some specific embodiments, the stirring speed is 1000 to 3000 rpm. For example, it can be 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, or any value within the range.

[0057] In the present invention, the above stirring can be achieved by magnetic stirring.

[0058] In some specific embodiments, the reaction time is 2 to 4 h. For example, it can be 2 h, 2.5 h, 3 h, 3.5 h, 4 h, or any value within the range.

[0059] It should be noted that the method for preparing solution B into a film in the present invention is a commonly used method in the art and is not specifically limited in the present invention. For example, solution B can be degassed under vacuum, then uniformly coated on a glass substrate with a film applicator, and after drying with hot air, the PVA film is peeled off to obtain it; or, solution B can be degassed under vacuum, then uniformly coated on a substrate material with a film bar, and a flat and uniform film coating can be obtained on the substrate after drying with hot air. The temperature for drying with hot air is not specifically limited. For example, it can be 60°C.

[0060] In the present invention, the thickness of the thin film is adjusted by controlling the parameters of the scraping knife in the scraping film machine, or a scraping rod of different specifications is used to scrape to a uniform required thickness.

[0061] In some preferred embodiments, before use, the substrate material is pre-cleaned with acetone and isopropyl alcohol to avoid the influence of contaminants such as dust on the uniformity and continuity of the thin film.

[0062] The water-blocking thin film and the preparation method thereof of the present invention will be described in detail below through several specific examples.

[0063] Example 1

[0064] This embodiment provides a water-blocking thin film, wherein the water-blocking thin film is a thin film prepared by modifying PVA with two-dimensional nanomaterials.

[0065] Its preparation method includes the following steps:

[0066] S1. Provide solution A of two-dimensional nanomaterials

[0067] 1.3 g (0.01 mol) of melamine is added to a 250 mL round-bottom flask, then 90 mL of an organic solvent (N,N-dimethylformamide) is added, and then 2.6 g (0.01 mol) of trimesoyl chloride is slowly added. After sealing, it is magnetically stirred at 2000 rpm for 3 h to obtain solution A of two-dimensional nanomaterials.

[0068] S2. Provide solution B of two-dimensional nanomaterial-modified PVA

[0069] Solution A of two-dimensional nanomaterials is filtered, 20 mL of the filtered solution A of two-dimensional nanomaterials is taken, 5 g of PVA is added, the temperature is raised to 90 °C, and it is continuously mechanically stirred at 200 rpm for 6 h under sealed conditions. After the reaction ends, the solution is cooled to room temperature to obtain solution B.

[0070] S3. Prepare the thin film from solution B

[0071] Solution B is degassed under vacuum, and then uniformly coated on a glass substrate with a scraping film machine. After being dried by hot air at 60 °C and then torn off, the water-blocking thin film is obtained.

[0072] Example 2

[0073] This embodiment provides a water-blocking thin film, wherein the water-blocking thin film is a thin film prepared by modifying PVA with two-dimensional nanomaterials.

[0074] Its preparation method includes the following steps:

[0075] S1. Provide solution A of two-dimensional nanomaterials

[0076] Add 5.2 g (0.04 mol) of melamine into a 250 mL round-bottom flask, then add 90 mL of organic solvent (N,N-dimethylacetamide), and then slowly add 2.6 g (0.01 mol) of trimesoyl chloride. Seal the flask and stir magnetically at 1000 rpm for 4 h to obtain solution A of the two-dimensional nanomaterial.

[0077] S2. Provide solution B of the two-dimensional nanomaterial-modified PVA

[0078] Filter solution A of the two-dimensional nanomaterial. Take 20 mL of the filtered solution A of the two-dimensional nanomaterial, add 1 g of PVA, heat up to 80 °C, and continue to stir mechanically at 100 rpm under sealed conditions for 8 h. After the reaction is completed, cool the solution to room temperature to obtain solution B.

[0079] S3. Prepare a film from solution B

[0080] Remove the air bubbles from solution B under vacuum, then uniformly coat it on a glass substrate with a film applicator, and tear it off after drying with hot air at 60 °C to obtain the water-blocking film.

[0081] Example 3

[0082] This example provides a water-blocking film, wherein the water-blocking film is a film prepared from two-dimensional nanomaterial-modified PVA.

[0083] Its preparation method includes the following steps:

[0084] S1. Provide solution A of the two-dimensional nanomaterial

[0085] Add 2.6 g (0.02 mol) of melamine into a 250 mL round-bottom flask, then add 90 mL of organic solvent (tetrahydrofuran), and then slowly add 2.6 g (0.01 mol) of trimesoyl chloride. Seal the flask and stir magnetically at 3000 rpm for 2 h to obtain solution A of the two-dimensional nanomaterial.

[0086] S2. Provide solution B of the two-dimensional nanomaterial-modified PVA

[0087] Filter solution A of the two-dimensional nanomaterial. Take 20 mL of the filtered solution A of the two-dimensional nanomaterial, add 2 g of PVA, heat up to 100 °C, and continue to stir mechanically at 300 rpm under sealed conditions for 4 h. After the reaction is completed, cool the solution to room temperature to obtain solution B.

[0088] S3. Prepare a film from solution B

[0089] Remove the air bubbles from solution B under vacuum, then uniformly coat it on a glass substrate with a film applicator, and tear it off after drying with hot air at 60 °C to obtain the water-blocking film.

[0090] Example 4

[0091] This embodiment provides a water-blocking film, wherein the water-blocking film is a film prepared from two-dimensional nanomaterial-modified PVA.

[0092] Its preparation method includes the following steps:

[0093] S1. Provide solution A of two-dimensional nanomaterials

[0094] Add 3.9 g (0.03 mol) of melamine to a 250 mL round-bottom flask, then add 90 mL of organic solvent (N-methylpyrrolidone), and then slowly add 2.6 g (0.01 mol) of trimesoyl chloride. After sealing, stir magnetically at 1500 rpm for 3.5 h to obtain solution A of two-dimensional nanomaterials.

[0095] S2. Provide solution B of two-dimensional nanomaterial-modified PVA

[0096] Filter solution A of two-dimensional nanomaterials, take 20 mL of the filtered solution A of two-dimensional nanomaterials, add 3 g of PVA, heat up to 85 °C, and continue to stir mechanically at 150 rpm for 7 h under sealed conditions. After the reaction is completed, cool the solution to room temperature to obtain solution B.

[0097] S3. Prepare the film from solution B

[0098] Remove the air bubbles from solution B under vacuum, then uniformly coat it on a glass substrate with a film applicator, and tear it off after drying with hot air at 60 °C to obtain the water-blocking film.

[0099] Example 5

[0100] This embodiment provides a water-blocking film, wherein the water-blocking film is a film prepared from two-dimensional nanomaterial-modified PVA.

[0101] Its preparation method includes the following steps:

[0102] S1. Provide solution A of two-dimensional nanomaterials

[0103] Add 3.9 g (0.03 mol) of melamine to a 250 mL round-bottom flask, then add 90 mL of organic solvent (N,N-dimethylformamide), and then slowly add 2.6 g (0.01 mol) of trimesoyl chloride. After sealing, stir magnetically at 2500 rpm for 2.5 h to obtain solution A of two-dimensional nanomaterials.

[0104] S2. Provide solution B of two-dimensional nanomaterial-modified PVA

[0105] Filter the solution A of two-dimensional nanomaterials. Take 20 mL of the filtered solution A of two-dimensional nanomaterials, add 4 g of PVA, heat it up to 95 °C, and continue to mechanically stir at 250 rpm for 5 h under sealed conditions. After the reaction, cool the solution to room temperature to obtain solution B.

[0106] S3. Prepare the solution B into a film

[0107] Debubble the solution B under vacuum, then evenly coat it on a glass substrate with a film coater, and tear it off after drying with hot air at 60 °C, thus obtaining the water-blocking film.

[0108] Comparative Example 1

[0109] In this comparative example, PVA (with a polymerization degree of 1700 and a degree of alcoholysis of 99%, supplied by Sichuan Vinylon Co., Ltd.) was directly dissolved in deionized water to prepare a PVA aqueous solution with a mass concentration of 10 wt%. Then, the PVA aqueous solution was debubbled under vacuum, and then evenly coated on a glass substrate with a film coater, and torn it off after drying with hot air at 60 °C, thus obtaining the PVA film.

[0110] Test Example 1

[0111] This test example investigated the performance of the water-blocking films prepared in each embodiment of the present invention and the existing PVA films.

[0112] Test method:

[0113] Use a film coater to make the water-blocking films and PVA films in each embodiment of the present invention into the thickness required by each standard for testing various performances. Specifically as follows:

[0114] The test standard for the water absorption rate of the film refers to ASTM D570-98, and the sample specifications are 76.2 mm × 25.4 mm × 3.2 mm.

[0115] The water vapor transmission rate of the film was tested according to the ASTM E96-2014 standard, and the sample specifications were a diameter of 70 mm and a thickness of 200 μm.

[0116] The oxygen transmission rate of the film was tested through the GB / T 1038-2000 standard, and the sample specifications were a diameter of 97 mm and a thickness of 100 μm.

[0117] The abrasion resistance of the film was tested using the Taber abrasion test method, following the GB / T30314-2019 standard, and the sample specifications were 50 mm × 50 mm × 1 mm.

[0118] The tensile ultimate strength of the film was tested according to GB / T 1040, and the sample specifications were 50 mm × 5 mm × 1 mm. The test results are shown in Table 1:

[0119] Table 1. Performance of the water-blocking films prepared in each example and the existing PVA films

[0120] As can be seen from the results in Table 1, compared with the PVA film of Comparative Example 1, the water-blocking film prepared by the method of the present invention not only has excellent water-blocking and oxygen-blocking properties, but also has more excellent wear resistance and mechanical properties.

[0121] So far, the technical solution of the present invention has been described in conjunction with the shown preferred embodiments. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims

1. A water-blocking film, characterized in that, The water-blocking film is a film prepared from two-dimensional nanomaterial-modified PVA.

2. A method for preparing the water-blocking film according to claim 1, characterized in that, The preparation method described above includes: Providing solution A of two-dimensional nanomaterials; Providing solution B of two-dimensional nanomaterial-modified PVA; Preparing solution B into a film.

3. The method for preparing a water-blocking film according to claim 2, wherein, Solution B is provided by the following method: First, filter solution A of two-dimensional nanomaterials, then add PVA to the filtered solution A of two-dimensional nanomaterials, raise the temperature to a preset temperature, stir at a preset speed for a preset time, and cool down to room temperature to obtain solution B.

4. The preparation method of the water-blocking film according to claim 3, characterized in that The mass-volume ratio of the PVA to solution A is (1-5) g: 20 mL in terms of g: mL; And / or, the preset temperature is 80-100 °C; And / or, the preset time is 4-8 h.

5. The method for preparing the water-blocking film according to claim 3, wherein The preset speed is 100-300 rpm.

6. The preparation method of the water-blocking film according to claim 2, characterized in that, Solution A of the two-dimensional nanomaterials is provided by the following method: In the presence of an organic solvent, react melamine and trimesoyl chloride under stirring to obtain solution A of the two-dimensional nanomaterials.

7. The method for preparing the water-blocking film according to claim 6, characterized in that, The molar ratio of the melamine to trimesoyl chloride is (1-4):

1.

8. The method for preparing the water-blocking film according to claim 6, wherein The organic solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide, tetrahydrofuran or N-methylpyrrolidone.

9. The method for preparing a water-blocking film according to claim 6, wherein The stirring speed is 1000-3000 rpm.

10. The method for preparing a water-blocking film according to claim 6, characterized in that, The reaction time is 2-4 h.

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