Transparent film and preparation method and application thereof

Abstract

The invention discloses a transparent film as well as a preparation method and application thereof, and relates to the technical field of high polymer materials. The transparent film is prepared from the following raw materials in percentage by mass: 3-5% of polyvinyl alcohol; 3-5% of a hydrogen bond solution; 1-5% of a cellulose nanocrystal solution; the hydrogen bond solution comprises a hydrogen bond acceptor and a hydrogen bond donor, and the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (1-2): 1; the mass concentration of the cellulose nanocrystal solution is 2-5%. The transparent film has the advantages of being degradable, high in performance, not prone to absorbing water in the environment and the like, the effect is guaranteed, and meanwhile the cost and the technological process can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a transparent film, a preparation method thereof, and an application thereof. Background Art

[0002] Polyvinyl alcohol (PVA) has attracted great attention due to its excellent water solubility and biodegradability, and is a green and environmentally friendly packaging material. However, the PVA material has some inherent defects, which limit its wider application. Since there are many hydroxyl groups in the side chain of PVA, it has high water absorption and poor water resistance, resulting in easy water absorption and swelling in a humid environment and performance degradation; at the same time, its strength is relatively low, making it difficult to meet the requirements of some high-strength application scenarios. Therefore, how to overcome the water absorption and strength problems of polyvinyl alcohol and prepare a new film material that not only meets the requirements of biodegradability but also has excellent properties has become an important topic in current materials science research. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a transparent film, a preparation method thereof, and an application thereof. A high-performance, low-water-absorbing, and biodegradable transparent film prepared by the present invention has the advantages of biodegradability, high performance, and low water absorption in the environment, and can reduce costs and the process while ensuring efficacy. At the same time, it can be applied in various different types of film fields, and has broad development prospects for both functional packaging and the electronics industry.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] In the first aspect, the present invention provides a transparent film, and the raw materials include the following components in mass percentage:

[0006] Polyvinyl alcohol 3-5%; hydrogen bond solution 3-5%; cellulose nanocrystal solution 1-5%;

[0007] The hydrogen bond solution includes a hydrogen bond acceptor and a hydrogen bond donor, and the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (1-2):1; the concentration of the cellulose nanocrystal solution is 2-5%.

[0008] The present invention uses polyvinyl alcohol as the main base material of the film to provide the film with basic biodegradable properties; by adding a hydrogen bond acceptor and a hydrogen bond donor, the two form a hydrogen bond network, significantly enhancing the intermolecular force of polyvinyl alcohol, thereby improving the strength and toughness of the film; by adding cellulose nanocrystals, not only the mechanical properties of the film are improved, but also the water absorption performance of the film is further improved through its unique nano effect. At the same time, the sulfonic acid groups and hydroxyl groups on the cellulose nanocrystals combine with the hydroxyl groups on the side chains of polyvinyl alcohol to form a stable three-dimensional network structure, making the molecular chains of the film closer, and it is difficult for water molecules to enter through the gaps between the films, and the bonds between the bonds are not easily broken, thereby improving the strength and toughness of the film and also helping to reduce production costs.

[0009] Therefore, by using the compounding of polyvinyl alcohol, cellulose nanocrystals and a hydrogen bond solution and controlling the concentration of the cellulose nanocrystals solution, the present invention not only helps to improve the strength and toughness of the film, but also makes the film have the characteristic of low water absorption.

[0010] Preferably, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 2:1.

[0011] Preferably, the concentration of the cellulose nanocrystals solution is any one or the range value of two of 2%, 3%, 4%, 5%.

[0012] Preferably, the diameter of the cellulose nanocrystals in the cellulose nanocrystals solution is 5 - 15 nm, and the length is 100 - 200 nm.

[0013] Preferably, the specific surface area of the cellulose nanocrystals in the cellulose nanocrystals solution is 180 - 240 m 2 / g.

[0014] By controlling the specific surface area of the cellulose nanocrystals within the above range, the present invention helps to adsorb and fix water molecules, thereby reducing the water absorption rate of the film.

[0015] Preferably, the pH of the cellulose nanocrystals solution is 5.5 - 6.5.

[0016] Preferably, the molecular weight of the polyvinyl alcohol is 63,800 - 114,000.

[0017] More preferably, the polyvinyl alcohol includes polyvinyl alcohol A with a molecular weight of 65,000 - 70,000 and polyvinyl alcohol B with a molecular weight of 85,000 - 100,000, and the mass ratio of the polyvinyl alcohol A to the polyvinyl alcohol B is (1 - 3):1.

[0018] The present invention uses a blend of polyvinyl alcohols with two different molecular weights. In the blend system, the polyvinyl alcohol with a high molecular weight has a long molecular chain and strong intermolecular forces, making it difficult to dissolve. On the other hand, the polyvinyl alcohol with a low molecular weight has a short molecular chain and weak intermolecular forces, which can dissolve relatively quickly to form a solvation layer, creating favorable conditions for the dissolution of the polyvinyl alcohol with a high molecular weight, promoting the dispersion and swelling of its molecular chains, accelerating the dissolution rate of the entire blend system, reducing the formation of local agglomeration and gels, and being conducive to improving the uniformity of the solution. At the same time, the hydroxyl groups on the cellulose nanocrystals can better combine with the hydroxyl groups on the side chains of polyvinyl alcohol to form a more uniform and stable three-dimensional network structure, making the molecular chains of the film closer, thereby further improving the waterproof performance and mechanical properties of the film.

[0019] Preferably, the hydrogen bond acceptor includes at least one of choline chloride and quaternary ammonium salts.

[0020] Preferably, the hydrogen bond donor includes at least one of glucose, urea, ethylene glycol, glycerol, 1,4-butanediol, triethylene glycol, D-sorbitol, xylitol, p-toluenesulfonic acid, oxalic acid, malonic acid, levulinic acid, malic acid, citric acid, tartaric acid, xylose, fructose, sucrose, and maltose.

[0021] Preferably, the concentration of the hydrogen bond solution is 0.1 - 0.3 g / mL. (The content of the hydrogen bond donor and the hydrogen bond acceptor in the hydrogen bond solution)

[0022] In a second aspect, the present invention also provides a method for preparing a transparent film, which includes the following steps:

[0023] (1) Dissolve polyvinyl alcohol in water for swelling, and heat to above 90 °C, stir until the solution is transparent to obtain a polyvinyl alcohol solution;

[0024] (2) Prepare a hydrogen bond acceptor solution and a hydrogen bond donor solution by separately dissolving the hydrogen bond acceptor and the hydrogen bond donor, and then mix the hydrogen bond acceptor solution and the hydrogen bond donor solution evenly to obtain a hydrogen bond solution;

[0025] (3) Then add the hydrogen bond solution to the polyvinyl alcohol solution, and mix evenly to obtain an initial solution;

[0026] (4) Finally, add the cellulose nanocrystal solution to the initial solution, mix evenly and dry to obtain the transparent film.

[0027] The present invention first prepares solutions of the hydrogen bond acceptor and the hydrogen bond donor separately, and then adds them to the polyvinyl alcohol solution and mixes with the cellulose nanocrystal solution. The method is simple and convenient, and is suitable for industrial production.

[0028] The thickness of the transparent film prepared by the present invention using the above method can reach 0.01 - 0.03 mm.

[0029] In a third aspect, the present invention also provides an application of the transparent film in packaging materials and electronic products.

[0030] Applying the prepared transparent film to packaging materials is beneficial to improving the strength and toughness of the packaging materials, and is also beneficial to improving the waterproof performance of the packaging materials.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. The present invention selects a degradable material - polyvinyl alcohol as the film-forming substrate, introduces the hydrogen bond binding between the hydrogen bond acceptor, hydrogen bond donor and polyvinyl alcohol, and the groups of cellulose nanocrystals and PVA form a three-dimensional network synergistic effect. The mutual interweaving makes the grain boundary strengthening effect of the film strong, and it is not easy to tear under the action of external force, which can meet the requirements of high performance of the film in different fields and has broad application prospects.

[0033] 2. The present invention provides a degradable transparent film with high strength and low water absorption. Among them, polyvinyl alcohol has strong hydrophilicity. By introducing a hydrogen bond donor, hydrogen bond acceptor and cellulose nanocrystals, and combining with some hydroxyl groups in polyvinyl alcohol to form a three-dimensional network structure, the molecular structure on the film surface is stable. By restricting the entry and diffusion of water molecules, the stability of the film in a humid environment is improved, thereby improving the problem of strong hydrophilicity of polyvinyl alcohol, and having excellent barrier properties. It has a shorter preparation time, lower cost and simpler process than the traditional preparation by plasma treatment and surface coating, so it is more convenient for industrial production. Specific Embodiments

[0034] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the protection scope and implementation manner of the present invention are not limited thereto.

[0035] The materials, reagents, etc. used in the following embodiments are, unless otherwise specified, reagents and materials that can be obtained from commercial channels.

[0036] Example 1

[0037] A method for preparing a transparent film includes the following steps:

[0038] (1) Dissolve 3 parts of polyvinyl alcohol (molecular weight of 114,000) in 91 parts of distilled water for swelling, add it to an oil bath pot and heat to 90 °C, stir until the solution is completely dissolved and transparent to obtain a polyvinyl alcohol solution;

[0039] (2) Prepare 50 mL of hydrogen bond solution: Weigh 3 g of anhydrous glucose and 4.633 g of choline chloride respectively, and the balance is water, with a total volume of 50 mL. The concentration of the hydrogen bond solution is 0.1527 g / mL, and the molar ratio of choline chloride to anhydrous glucose is 2:1;

[0040] (3) Then add 4 parts of the hydrogen bond solution to the polyvinyl alcohol solution, and after mixing evenly, an initial solution is obtained;

[0041] (4) Finally, add 2 parts of the cellulose nanocrystal solution (pH = 5.5) to the initial solution, mix evenly, pour it into a mold, and bake it in a constant temperature and humidity box at 70 °C for 3 h. After cooling to room temperature, a transparent film is obtained;

[0042] Among them, the thickness of the transparent film is 0.01 mm; the mass concentration of the cellulose nanocrystal solution is 2%, the diameter of the cellulose nanocrystals is 5 - 15 nm, and the length is 100 - 200 nm.

[0043] Example 2

[0044] A method for preparing a transparent film, comprising the following steps:

[0045] (1) Dissolve 5 parts of polyvinyl alcohol (molecular weight of 63,700) in 90 parts of distilled water for swelling, add it to an oil bath and heat to 90 °C, and stir until the solution is completely dissolved and transparent to obtain a polyvinyl alcohol solution;

[0046] (2) Prepare 50 mL of hydrogen bond solution: Weigh 3 g of anhydrous glucose and 4.633 g of choline chloride respectively, with the balance being water, and the total volume is 50 mL. The concentration of the hydrogen bond solution is 0.1527 g / mL, and the molar ratio of choline chloride to anhydrous glucose is 2:1;

[0047] (3) Then add 3 parts of the hydrogen bond solution to the polyvinyl alcohol solution, and after mixing evenly, an initial solution is obtained;

[0048] (4) Finally, add 2 parts of the cellulose nanocrystal solution (pH = 6.5) to the initial solution, mix evenly, pour it into a mold, and bake it in a constant temperature and humidity box at 70 °C for 3 h. After cooling to room temperature, a transparent film is obtained;

[0049] Among them, the thickness of the transparent film is 0.02 mm; the mass concentration of the cellulose nanocrystal solution is 3%, the diameter of the cellulose nanocrystals is 5 - 15 nm, and the length is 100 - 200 nm.

[0050] Example 3

[0051] A method for preparing a transparent film, comprising the following steps:

[0052] (1) Dissolve 4 parts of polyvinyl alcohol (molecular weight of 100,000) in 89 parts of distilled water for swelling, add it to an oil bath and heat to 90 °C, and stir until the solution is completely dissolved and transparent to obtain a polyvinyl alcohol solution;

[0053] (2) Prepare 50 mL of hydrogen bond solution: Weigh 3 g of anhydrous glucose and 4.633 g of choline chloride respectively. The balance is water, with a total volume of 50 mL. The concentration of the hydrogen bond solution is 0.1527 g / mL, and the molar ratio of choline chloride to anhydrous glucose is 2:1;

[0054] (3) Then add 5 parts of the hydrogen bond solution to the polyvinyl alcohol solution and mix evenly to obtain the initial solution;

[0055] (4) Finally, add 2 parts of the cellulose nanocrystal solution (pH = 5.5) to the initial solution, mix evenly, pour it into a mold, and dry it in a constant temperature and humidity box at 70 °C for 3 h. After cooling to room temperature, a transparent film is obtained;

[0056] Among them, the thickness of the transparent film is 0.03 mm; the mass concentration of the cellulose nanocrystal solution is 5%, the diameter of the cellulose nanocrystals is 5 - 15 nm, and the length is 100 - 200 nm.

[0057] Example 4

[0058] A method for preparing a transparent film, which is different from Example 1 in that in step (1), 3 parts of polyvinyl alcohol are dissolved in 92 parts of distilled water for swelling; in step (3), 4 parts of the hydrogen bond solution are added to the polyvinyl alcohol solution; in step (4), 1 part of the cellulose nanocrystal solution (pH = 5.5) is added to the initial solution, and the others are the same as in Example 1.

[0059] Example 5

[0060] A method for preparing a transparent film, which is different from Example 1 in that in step (1), 3 parts of polyvinyl alcohol are dissolved in 90 parts of distilled water for swelling; in step (3), 4 parts of the hydrogen bond solution are added to the polyvinyl alcohol solution; in step (4), 3 parts of the cellulose nanocrystal solution (pH = 5.5) are added to the initial solution, and the others are the same as in Example 1.

[0061] Example 6

[0062] A method for preparing a transparent film, which is different from Example 1 in that in step (1), 3 parts of polyvinyl alcohol are dissolved in 89 parts of distilled water for swelling; in step (3), 4 parts of the hydrogen bond solution are added to the polyvinyl alcohol solution; in step (4), 4 parts of the cellulose nanocrystal solution (pH = 5.5) are added to the initial solution, and the others are the same as in Example 1.

[0063] Example 7

[0064] A method for preparing a transparent film, which is different from Example 1 in that in step (1), 3 parts of polyvinyl alcohol are dissolved in 88 parts of distilled water for swelling; in step (3), 4 parts of a hydrogen bond solution are added to the polyvinyl alcohol solution; in step (4), 5 parts of a cellulose nanocrystal solution (pH = 5.5) are added to the initial solution, and the rest are the same as in Example 1.

[0065] Example 8

[0066] A method for preparing a transparent film, which is different from Example 1 in that in step (1), the polyvinyl alcohol includes polyvinyl alcohol A with a molecular weight of 65,000 - 70,000 and polyvinyl alcohol B with a molecular weight of 85,000 - 100,000, and the mass ratio of polyvinyl alcohol A to polyvinyl alcohol B is 1:1.

[0067] Example 9

[0068] A method for preparing a transparent film, which is different from Example 1 in that in step (1), the polyvinyl alcohol includes polyvinyl alcohol A with a molecular weight of 65,000 - 70,000 and polyvinyl alcohol B with a molecular weight of 85,000 - 100,000, and the mass ratio of polyvinyl alcohol A to polyvinyl alcohol B is 3:1.

[0069] Comparative Example 1

[0070] A method for preparing a transparent film includes the following steps:

[0071] (1) Dissolve 3 parts of polyvinyl alcohol in 97 parts of distilled water for swelling, add it to an oil bath pot and heat to 90 °C, stir until the solution is completely dissolved and transparent to obtain a polyvinyl alcohol solution;

[0072] (2) Pour the polyvinyl alcohol solution into a mold and bake it in a constant temperature and humidity box at 70 °C for 3 h, and obtain a transparent film after cooling to room temperature.

[0073] Comparative Example 2

[0074] A method for preparing a transparent film includes the following steps:

[0075] (1) Dissolve 3 parts of polyvinyl alcohol in 93 parts of distilled water for swelling, add it to an oil bath pot and heat to 90 °C, stir until the solution is completely dissolved and transparent to obtain a polyvinyl alcohol solution;

[0076] (2) Prepare 50 mL of a hydrogen bond solution: Weigh 3 g of anhydrous glucose and 4.633 g of choline chloride respectively, and the balance is water, with a total volume of 50 mL. The concentration of the hydrogen bond solution is 0.1527 g / mL, and the molar ratio of choline chloride to anhydrous glucose is 2:1;

[0077] (3) Then add 4 parts of the hydrogen bond solution to the polyvinyl alcohol solution, and mix evenly to obtain an initial solution;

[0078] (4) Pour the initial solution into a mold and dry it in a thermostatic and humidity-controlled oven at 70 °C for 3 h. After cooling to room temperature, a transparent film is obtained; the thickness of the transparent film is 0.01 mm.

[0079] The difference between this comparative example and Example 1 is only that no cellulose nanocrystal solution is added in this comparative example.

[0080] Comparative Example 3

[0081] A method for preparing a transparent film, which is different from Example 1 in that in step (1), 1 part of polyvinyl alcohol is dissolved in 89 parts of distilled water for swelling; in step (3), 8 parts of a hydrogen bond solution are added to the polyvinyl alcohol solution; in step (4), 2 parts of a cellulose nanocrystal solution (pH = 5.5) are added to the initial solution, and the others are the same as in Example 1.

[0082] Comparative Example 4

[0083] A method for preparing a transparent film, which is different from Example 1 in that in step (1), 8 parts of polyvinyl alcohol are dissolved in 89 parts of distilled water for swelling; in step (3), 1 part of a hydrogen bond solution is added to the polyvinyl alcohol solution; in step (4), 2 parts of a cellulose nanocrystal solution (pH = 5.5) are added to the initial solution, and the others are the same as in Example 1.

[0084] Comparative Example 5

[0085] A method for preparing a transparent film, which is different from Example 1 in that in step (1), 3 parts of polyvinyl alcohol are dissolved in 85 parts of distilled water for swelling; in step (3), 4 parts of a hydrogen bond solution are added to the polyvinyl alcohol solution; in step (4), 8 parts of a cellulose nanocrystal solution (pH = 5.5) are added to the initial solution, and the others are the same as in Example 1.

[0086] Comparative Example 6

[0087] A method for preparing a transparent film, which is different from Example 1 in that in step (1), 3 parts of polyvinyl alcohol are dissolved in 92.8 parts of distilled water for swelling; in step (3), 4 parts of a hydrogen bond solution are added to the polyvinyl alcohol solution; in step (4), 0.2 parts of a cellulose nanocrystal solution (pH = 5.5) are added to the initial solution, and the others are the same as in Example 1.

[0088] Experiment

[0089] 1. Testing of mechanical properties:

[0090] According to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3", select films without bubbles and smooth surfaces, cut them into strip-shaped specimens with a width of 30 mm and a length of 150 mm using a die cutter, install them on a microcomputer-controlled electronic universal testing machine to conduct tests on elongation at break (EB) and tensile strength (TS). Input the film thickness (measure the average value of 5 points respectively), and stretch the film material at a speed of 200 mm / min until the sample is broken. During the testing process, the computer records the data, and the EB value and TS value are directly read from the computer. Measure 5 groups of data for each group of samples and take the average value.

[0091] 2. Test of water absorption:

[0092] Test the water absorption of the film according to GB / T 1034-2008. Cut the prepared film into strips with a length of 3 cm and a width of 3 cm, place them in a vacuum drying oven at 50 °C for 24 h, take them out and immediately put them into a desiccator to cool to room temperature, and weigh their dry weight W0; lay the sample flat on a bottle, place the bottle with the sample in a desiccator containing a small amount of distilled water, seal it and place it for 24 h, take it out and weigh its weight W1 after water absorption, then:

[0093] Water absorption rate (%) = (W1 - W0) × 100% / W0

[0094] In the formula: W0 and W1 are the masses of the sample before and after water absorption (g)

[0095] 3. Test of moisture permeability:

[0096] Test the moisture permeability rate of the film according to GB / T 16928-1997. Cut the prepared film into a square with a size of 4 cm × 4 cm, weigh 3 g of anhydrous calcium chloride and place it in a weighing bottle (25 × 40 mm) that has been dried to a constant weight. Cover the sample film on the container containing anhydrous calcium chloride and fix it at the mouth of the container with a rubber elastic cord. After weighing, record the mass as m1, then put it into a constant temperature and humidity chamber at 25 °C and 90% RH, take it out after 24 h, and immediately weigh it. Record the weight as m2, then: Film moisture permeability rate Q(H2O) = (m2 - m1) / t × s

[0097] In the formula: The unit of Q(H2O) is g / (m2·h); s is the film covering area / m2; m1 and m2 are the masses of the weighing bottle before and after weighing (g); t is the time (h).

[0098] 4. Test of opacity:

[0099] Place the membrane sample (a 1 cm × 4 cm strip) in a cuvette and measure the absorbance (A) of the membrane at 600 nm in a UV spectrophotometer. Use the cuvette without the sample as a reference. The opacity of the sample membrane is calculated according to the following formula. (Measure the thickness first and then the absorbance. Randomly take 3 points to measure the thickness and take the average value.)

[0100] O = Abs600 / L

[0101] Where: O - opacity (A mm-1); Abs600 - absorbance of the membrane at 600 nm; L - thickness of the membrane (mm)

[0102] The above experimental results are all shown in Table 1.

[0103] Table 1

[0104]

[0105]

[0106] From the comparison of Comparative Examples 1-5 with Example 1 respectively, it can be seen that in Comparative Example 1, the hydrogen bond solution and the cellulose nanocrystal solution were not added. In Comparative Example 2, the cellulose nanocrystal solution was not added. In Comparative Examples 3-4, the dosages of polyvinyl alcohol and the hydrogen bond solution were not within the scope defined in the present invention. In Comparative Example 5, the dosage of the cellulose nanocrystal solution was not within the scope defined in the present invention. The mechanical properties of the films in Comparative Examples 1-5 were all inferior to those of Example 1, and the water absorption of the films was much higher than that of Example 1. This shows that by compounding polyvinyl alcohol, the cellulose nanocrystal solution and the hydrogen bond solution and controlling the ratios of the polyvinyl alcohol, the cellulose nanocrystal solution and the hydrogen bond solution within the scope defined in the present invention, it is not only beneficial to improve the mechanical properties of the film, but also beneficial to improve the waterproof performance of the film. At the same time, it also makes the film have a high transparency.

[0107] Comparing Comparative Examples 5-6 with Example 1 respectively, it can be seen that the content of cellulose nanocrystals in Comparative Example 5 is too high, and the content of cellulose nanocrystals in Comparative Example 6 is too low. The mechanical properties of the films in Comparative Examples 5-6 both decrease, and the water absorption increases, indicating that the content of cellulose nanocrystals affects the mechanical properties and waterproof properties of the films. This is because when the content of cellulose nanocrystals is too low, the content of hydroxyl groups in cellulose nanocrystals is too small to form a stable and uniform three-dimensional network structure with the hydroxyl groups on the side chains of polyvinyl alcohol well, resulting in a decrease in both the waterproof property and the mechanical property of the film. When the content of cellulose nanocrystals is too high, the interaction between cellulose nanocrystals is enhanced, which easily leads to aggregation or overlap, weakening the interfacial interaction between cellulose nanocrystals and polyvinyl alcohol, thus affecting the properties of the film. Therefore, by controlling the content of cellulose nanocrystals within the range defined in the present invention, it is beneficial to improve the mechanical properties and waterproof properties of the film.

[0108] As can be seen from Examples 1-7, in the present invention, by simultaneously adding polyvinyl alcohol, cellulose nanocrystal solution and hydrogen bond solution and coordinating them with each other, controlling the ratios of polyvinyl alcohol, cellulose nanocrystal solution and hydrogen bond solution, and simultaneously controlling the concentration of cellulose nanocrystal solution, the film has excellent mechanical properties and waterproof properties at the same time, and also has high transparency.

[0109] Comparing Examples 8-9 with Example 1 respectively, it can be obtained that in Examples 8-9, two polyvinyl alcohols with different molecular weights are compounded. The polyvinyl alcohols with different molecular weights can interpenetrate, disperse and form a more uniform mixed system in water, which is beneficial to further improve the mechanical properties and waterproof properties of the film.

[0110] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A transparent film, characterized in that, The raw materials include components in the following mass percentages: Polyvinyl alcohol 3 - 5%; Hydrogen bond solution 3 - 5%; Cellulose nanocrystal solution 1 - 5%; The hydrogen bond solution includes a hydrogen bond acceptor and a hydrogen bond donor, and the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (1 - 2):1; The mass concentration of the cellulose nanocrystal solution is 2 - 5%.

2. The transparent film according to claim 1, wherein The concentration of the hydrogen bond solution is 0.1 - 0.3 g / mL.

3. The transparent film according to claim 1, wherein, In the cellulose nanocrystal solution, the diameter of the cellulose nanocrystals is 5 - 15 nm, and the length is 100 - 200 nm.

4. The transparent film according to claim 1, wherein, The specific surface area of the cellulose nanocrystals in the cellulose nanocrystal solution is 180 - 240 m 2 / g.

5. The transparent film according to claim 1, wherein The molecular weight of the polyvinyl alcohol is 63,800 - 114,000.

6. The transparent thin film according to claim 5, wherein, The polyvinyl alcohol includes polyvinyl alcohol A with a molecular weight of 65,000 - 70,000 and polyvinyl alcohol B with a molecular weight of 85,000 - 100,000, and the mass ratio of polyvinyl alcohol A to polyvinyl alcohol B is (1 - 3):

1.

7. The transparent thin film according to claim 1, wherein The hydrogen bond acceptor includes at least one of choline chloride and quaternary ammonium salts.

8. The transparent thin film according to claim 1, wherein The hydrogen bond donor includes at least one of glucose, urea, ethylene glycol, glycerol, 1,4 - butanediol, triethylene glycol, D - sorbitol, xylitol, p - toluenesulfonic acid, oxalic acid, malonic acid, levulinic acid, malic acid, citric acid, tartaric acid, xylose, fructose, sucrose, and maltose.

9. The preparation method of the transparent film according to any one of claims 1-8, characterized in that, It includes the following steps: (1) Dissolve polyvinyl alcohol in water for swelling, and heat it to above 90°C, stir until the solution is transparent to obtain a polyvinyl alcohol solution; (2) Prepare a hydrogen bond acceptor solution and a hydrogen bond donor solution from the hydrogen bond acceptor and the hydrogen bond donor respectively, and then mix the hydrogen bond acceptor solution and the hydrogen bond donor solution evenly to obtain a hydrogen bond solution; (3) Then add the hydrogen bond solution to the polyvinyl alcohol solution, and mix evenly to obtain an initial solution; (4) Finally, add the cellulose nanocrystal solution to the initial solution, mix evenly and dry it to obtain a transparent film.

10. Application of the transparent film according to any one of claims 1 - 8 in packaging materials and electronic products.

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