Transparent wood film based on gelatin vacuum impregnated wood and preparation method of transparent wood film

Abstract

The invention discloses a transparent wood film based on gelatin vacuum impregnated wood and a preparation method of the transparent wood film, and belongs to the technical field of bio-based composite materials. Comprising the following steps that wood is pretreated, and a framework material with porous cellulose reserved is obtained; and the framework material is subjected to freeze drying, then is subjected to vacuum impregnation in a gelatin solution, is flatly laid and is naturally aired, and the transparent wood film based on the gelatin vacuum impregnation wood is obtained. By optimizing a lignin removal process and a gelatin vacuum impregnation technology and combining a physical crosslinking strategy, efficient preparation of the transparent wood film is successfully realized. The innovative method not only overcomes many defects of a traditional process, but also endows the material with excellent environmental protection property and use performance, and opens up a new way for large-scale application of the transparent wood.

Description

Technical Field

[0001] The present invention belongs to the technical field of bio-based composite materials, and particularly relates to a transparent wood film based on vacuum impregnation of wood with gelatin and a preparation method thereof. Background Art

[0002] As an emerging bio-based material, transparent wood has shown broad application prospects in the fields of architecture, packaging, optoelectronics, etc. in recent years due to its unique optical properties, lightweight characteristics, and excellent mechanical properties. The preparation of traditional transparent wood mainly relies on two key steps: first, removing the light-absorbing components in wood through chemical treatment (such as delignification), and then filling the porous structure of wood with synthetic resins (such as epoxy resins) to achieve optical transparency. However, this traditional method has several limitations: firstly, synthetic polymer materials such as epoxy resins are costly and difficult to biodegrade, which is not conducive to the sustainable development of materials; secondly, the interfacial compatibility between the resin and the wood matrix is poor, which easily leads to a decline in material properties; in addition, existing processes often require the use of toxic chemical reagents or involve complex cross-linking steps, which not only increases production costs but also limits the environmental friendliness and large-scale application of materials. Summary of the Invention

[0003] Based on the above background, the present invention proposes a transparent wood film based on vacuum impregnation of wood with gelatin and a preparation method thereof. This method successfully realizes the efficient preparation of the transparent wood film by optimizing the lignin removal process, freeze-drying and vacuum impregnation technology with gelatin, and combining physical cross-linking strategies. This innovative method not only overcomes many defects of traditional processes but also endows the material with excellent environmental friendliness and service performance, opening up a new way for the large-scale application of transparent wood.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] One of the objects of the present invention is to provide a preparation method of a transparent wood film based on vacuum impregnation of wood with gelatin, comprising the following steps: pretreating the wood to obtain a skeleton material retaining porous cellulose; freeze-drying the skeleton material, then vacuum impregnating it in a gelatin solution, and spreading it out to dry naturally to obtain a transparent wood film based on vacuum impregnation of wood with gelatin.

[0006] The present invention first pre-treats wood, selectively removing lignin and hemicellulose and retaining the porous cellulose skeleton. Subsequently, through freeze-drying, the water in the wood is first frozen into a solid state, and then the ice directly sublimes under vacuum conditions, thereby removing the water. This method can effectively avoid the pore collapse caused by the liquid surface tension during the traditional drying process and retain the porous cellulose skeleton structure of the wood. During the freeze-drying process, the pore structure inside the wood is completely retained, providing sufficient space and channels for the subsequent impregnation of the gelatin solution, ensuring that the gelatin can uniformly fill the pores. Moreover, the wood skeleton after freeze-drying has a high porosity and an open pore structure, which is conducive to the more efficient penetration and filling of the gelatin solution into the pores during the vacuum impregnation process, forming a uniform transparent phase. Then, the gelatin solution is infiltrated into the nano / micro pores of the delignified wood through vacuum and pressure impregnation. After cooling, the gelatin forms a gel state, physically fills and solidifies, occupying the internal pores of the wood and forming a continuous transparent phase. During this process, the gelatin and cellulose enhance the interfacial bonding through physical cross-linking, significantly improving the material stability. At the same time, the amino groups (-NH2) and hydroxyl groups (-OH) in the gelatin form hydrogen bonds with the hydroxyl groups on the surface of the cellulose, further enhancing the interfacial bonding force and reducing the light scattering (Rayleigh scattering) at the cellulose-air interface, enabling the light to effectively penetrate. Finally, the sample after vacuum impregnation is laid flat and naturally dried to obtain a transparent wood film based on gelatin vacuum-impregnated wood. The delignified cellulose skeleton provides mechanical support for the material, while the gelatin fills the pores and matches the refractive index, forming a transparent and high-strength wood film composite material.

[0007] Furthermore, the pre-treatment includes pre-treatment with a mixed solution of sodium hydroxide and sodium sulfite and pre-treatment with sodium chlorite solution, that is, sequentially performing pre-treatment with a mixed solution of sodium hydroxide and sodium sulfite and pre-treatment with sodium chlorite solution.

[0008] Furthermore, the specific steps of the pre-treatment with a mixed solution of sodium hydroxide and sodium sulfite include:

[0009] Cut the wood into thin slices and soak them in deionized water for softening treatment to obtain softened wood slices;

[0010] Dissolve sodium hydroxide and sodium sulfite in deionized water to obtain a mixed solution;

[0011] Immerse the wood slices in the mixed solution, heat them in a water bath, take out the wood slices and wash them with deionized water to obtain a semi-pre-treated sample.

[0012] Even further, the size of the cutting is: 4 cm × 4 cm × 1 mm; and / or

[0013] The time of the softening treatment is 12 hours; and / or

[0014] During the preparation of the mixed solution, the dosage ratio of sodium hydroxide, sodium sulfite and deionized water is 1 g∶0.4 g∶10 mL; and / or

[0015] The conditions for water bath heating are: water bath heating at 100 °C for 3 - 5 hours; and / or

[0016] The number of washing times is 3 times.

[0017] Furthermore, the specific steps of the pretreatment with sodium chlorite solution include:

[0018] Dissolve sodium chlorite in deionized water, adjust the pH to acidic to obtain a sodium chlorite solution;

[0019] Immerse the sample pretreated with the mixed solution of sodium hydroxide and sodium sulfite in the sodium chlorite solution, continue water bath heating, take out the wood chips and wash them with deionized water to complete the pretreatment.

[0020] Even further, during the preparation of the sodium chlorite solution, the dosage ratio of sodium chlorite and deionized water is 1 g∶25 mL; and / or

[0021] The pH value is 4; and / or

[0022] The conditions for the continued water bath heating are: water bath heating at 80 °C for 1 - 3 hours; and / or

[0023] The number of washing times is 3 times for all.

[0024] Furthermore, the conditions for freeze-drying are: freeze-preserve at -18 °C for 30 minutes, and then put it into a freeze-dryer at -25 °C and keep it for 12 hours. Freeze-preserving first can enable the wood to better maintain its porous structure, which is beneficial to the entry of gelatin.

[0025] Furthermore, the conditions for vacuum impregnation are: vacuum impregnation at -0.8 MPa for 0.5 hour.

[0026] Furthermore, the preparation process of the gelatin solution is: add gelatin to deionized water, stir at 60 °C in a water bath for 10 minutes to obtain a gelatin solution; wherein, the dosage ratio of gelatin to deionized water is (1 - 5) g∶100 mL.

[0027] The second object of the present invention is to provide a transparent wood film based on gelatin-vacuum-impregnated wood prepared by the above preparation method.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] (1) High-efficiency delignification process: Through the synergistic oxidation system of sodium hydroxide - sodium chlorite, rapid delignification of lignin is achieved while maintaining the structural integrity of cellulose;

[0030] (2) Gelatin refractive index matching: Utilize the similar refractive indices of gelatin and cellulose to reduce light scattering and enhance transparency (light transmittance > 21%);

[0031] (3) Hydrogen bond crosslinking enhancement: Hydrogen bond networks are formed between the amino and hydroxyl groups in gelatin molecules and the hydroxyl groups on the cellulose surface, significantly improving the tensile strength (≥353.4 MPa). BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings forming a part of this invention are used to provide a further understanding of the invention. The schematic embodiments and descriptions thereof of the invention are used to explain the invention and do not constitute an improper limitation of the invention. In the drawings:

[0033] Figure 1 It is the infrared spectrum diagram of the log in Example 1;

[0034] Figure 2 It is the infrared spectrum diagram of the delignified wood obtained by freeze-drying treatment in Example 1;

[0035] Figure 3 It is the infrared spectrum diagram of the transparent wood film based on gelatin-vacuum impregnated wood prepared in Example 1;

[0036] Figure 4 It is the stress-strain diagram of the log, delignified wood, and transparent wood film in Example 1 of the present invention;

[0037] Figure 5 It is the ultraviolet spectrum diagram of the log, delignified wood, and transparent wood film in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0039] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0040] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0041] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the description of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the description of this invention are obvious to those skilled in the art. The description and examples of this invention are merely exemplary.

[0042] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0043] As a natural biopolymer, gelatin has attracted much attention due to its unique advantages: First, gelatin has excellent film-forming properties and biocompatibility, and is completely biodegradable, meeting the development trend of green materials; Second, the refractive index of gelatin (about 1.53) highly matches that of cellulose, the main component of wood (about 1.53). This property can significantly reduce the light scattering at the material interface, which is beneficial to improving transparency; In addition, gelatin molecules contain abundant active groups, facilitating modification by physical or chemical methods, providing the possibility for regulating the material properties. However, despite many advantages of gelatin, there has been no reported systematic method for preparing transparent wood films by impregnating delignified wood with gelatin.

[0044] Based on this, the present invention discloses a transparent wood film based on vacuum impregnation of wood with gelatin and its preparation method. The transparent wood film is composed of gelatin and balsa wood with partial removal of lignin and hemicellulose, and is cross-linked through hydrogen bonding. The transparent wood film of the present invention has properties such as high transparency and high tensile strength. After pretreatment of the raw materials, lignin and hemicellulose are selectively removed through chemical treatment (such as sodium hydroxide, sodium sulfite, sodium chlorite, etc.), and the porous cellulose skeleton is retained. By vacuum impregnating with gelatin, a transparent wood film with properties such as high transparency and high tensile strength is formed. The raw materials used in the present invention are safe and environmentally friendly, and the transparent wood film has properties such as high transparency and high tensile strength.

[0045] The embodiment of the present invention provides a preparation method of a transparent wood film based on vacuum impregnation of wood with gelatin, comprising the following steps:

[0046] (1) Pretreatment:

[0047] S1. Cut the wood (balsa wood) into 4 cm × 4 cm × 1 mm thin slices and soak them in deionized water for 12 hours to soften. Take 80 g of sodium hydroxide and 32 g of sodium sulfite and place them in a 1000 mL glass beaker. Add 800 mL of deionized water and dissolve them thoroughly to obtain a mixed solution of sodium hydroxide and sodium sulfite. Place the softened wood with a thickness of 1 mm into the mixed solution of sodium hydroxide and sodium sulfite and ensure that the solution completely submerges the sample. Seal the glass beaker with plastic wrap and keep it in a water bath at a temperature of 100 °C for 3 - 5 hours (such as 3 hours, 4 hours, or 5 hours). Take out the wood and wash it 3 times with deionized water to obtain sample A;

[0048] S2. Take 16 g of sodium chlorite and 400 mL of deionized water and place them in a 1000 mL glass beaker to dissolve them thoroughly to obtain a sodium chlorite solution. Adjust its pH value to 4. Then place sample A into this solution and ensure that the solution completely submerges the sample. Seal the glass beaker with plastic wrap and keep it in a water bath at a temperature of 80 °C for 1 - 3 hours (such as 1 hour, 2 hours, or 3 hours). Take out the wood and wash it 3 times with deionized water;

[0049] (2) Freeze - drying: Freeze - preserve the pretreated wood sample at - 18 °C for 30 minutes, and then put it into a freeze - dryer at - 25 °C for 12 hours to obtain a dry wood sample with partial lignin and hemicellulose removed;

[0050] (3) Gelatin vacuum impregnation: Dissolve 1 - 5 g of gelatin (such as 1 g, 2 g, 2.5 g, 3 g, 4 g, or 5 g) in 100 mL of deionized water and stir it in a water bath at 60 °C for 10 minutes until all the gelatin is dissolved. Place the obtained gelatin solution and the prepared dry wood sample in a vacuum device (- 0.8 MPa) for impregnation for 0.5 hour. After filling, the pores inside the wood are occupied by gelatin, reducing the light scattering (Rayleigh scattering) at the cellulose - air interface and enabling light to penetrate.

[0051] (4) Take out the sample after the vacuum impregnation is completed, lay it flat, and let it dry naturally to obtain a transparent wood film based on gelatin - vacuum - impregnated wood.

[0052] All the raw materials used in the present invention are obtained by purchasing on the market.

[0053] The technical solution of the present invention is further described below through examples.

[0054] Example 1

[0055] A preparation method of a transparent wood film based on gelatin - vacuum - impregnated wood, comprising the following steps:

[0056] (1) Pretreatment:

[0057] S1. Cut balsa wood (balsa log) into 4 cm × 4 cm × 1 mm slices and soak them in deionized water for 12 hours to soften them; take 80 g of sodium hydroxide and 32 g of sodium sulfite and put them in a 1000 mL glass beaker, add 800 mL of deionized water and fully dissolve them to obtain a mixed solution of sodium hydroxide and sodium sulfite; place the softened balsa wood with a thickness of 1 mm in the mixed solution of sodium hydroxide and sodium sulfite and ensure that the solution completely immerses the sample, seal the glass beaker with plastic wrap and keep it in a water bath at 100° C. for 4 hours, take out the balsa wood and wash it 3 times with deionized water to obtain sample A;

[0058] S2. Take 16 g of sodium chlorite and 400 mL of deionized water and place them in a 1000 mL glass beaker to fully dissolve them to obtain a sodium chlorite solution, adjust its pH value to 4, then place sample A in the solution and ensure that the solution completely immerses the sample, cover the glass beaker with plastic wrap and keep it in a water bath at 80° C. for 2 hours, take out the balsa wood and wash it 3 times with deionized water;

[0059] (2) Freeze drying: The pretreated balsa wood sample was frozen at -18 °C for 30 minutes and then placed in a -25 °C freeze dryer for 12 hours to obtain a dry wood sample with lignin and hemicellulose partially removed (recorded as delignified wood);

[0060] (3) Gelatin vacuum impregnation: Dissolve 3 g of gelatin in 100 mL of deionized water and stir in a 60°C water bath for 10 minutes until the gelatin is completely dissolved; place the obtained gelatin solution and the prepared dry wood sample in a vacuum device (-0.8 MPa) and immerse for 0.5 hour. After the vacuum impregnation, take out the sample and lay it flat to dry naturally to obtain a transparent wood film based on gelatin vacuum impregnated wood.

[0061] Figure 1 is the infrared spectrum of the log in Example 1, Figure 2 is the infrared spectrum of the delignified wood obtained by freeze-drying in Example 1, Figure 3 This is the infrared spectrum of the transparent wood film based on the gelatin vacuum impregnation wood prepared in Example 1. Figure 1 It can be seen that at 1157cm -1 At 1423cm -1 At 1635cm, the benzene ring skeleton vibration and C-H plane bending vibration work together, and the source is lignin; -1 The peaks at 100° and 100° are carbonyl conjugated aromatic ketone C=O stretching vibration peaks, which are derived from hemicellulose. These characteristic peaks strongly support the characteristics of the original wood. Figure 3 The prepared transparent wood film can be clearly observed at 1544 cm-1 The stretching vibration peak of CN appeared at , which indicates that gelatin has been successfully impregnated into the film. Figure 2 and Figure 3 It can be found that the -OH peak becomes broadened, which indicates that hydrogen bonds are formed between gelatin and delignified wood after gelatin filling, further proving the successful impregnation of gelatin.

[0062] The transparent wood film prepared in Example 1 was tested for mechanical properties. The testing method was as follows: using a universal material testing machine to measure the tensile strength. The transparent wood film sample parameters were: 20 mm long, 6.5 mm wide, 0.08 mm thick, a tensile speed of 150 mm / min, a maximum force of 184.91 N, and a displacement of 9.05 mm.

[0063] Figure 4 The strain-stress diagram of logs, delignified wood and transparent wood film in Example 1 of the present invention is shown in Figure 1. The tensile strength of logs is 7.8MPa, the tensile strength of delignified wood is 3.2MPa, and the tensile strength of transparent wood film after impregnation with gelatin reaches 353.4MPa. It can be seen that the strength is increased by dozens of times, forming a transparent and high-strength transparent wood film composite material.

[0064] Figure 5 The UV spectra of logs, delignified wood and transparent wood film in Example 1 of the present invention are shown in Figure 1. The light transmittance of logs is 0%, the light transmittance of delignified wood is 0%, and the light transmittance of transparent wood film after impregnation with gelatin reaches 21.3%. It can be seen that the transparency is greatly improved, forming a transparent and high-strength transparent wood film composite material.

[0065] Example 2

[0066] A method for preparing a transparent wood film based on vacuum impregnation of wood with gelatin comprises the following steps:

[0067] (1) Pretreatment:

[0068] S1. Cut balsa wood (log) into 4cm×4cm×1mm slices and soak them in deionized water for 12 hours to soften them; put 80g of sodium hydroxide and 32g of sodium sulfite in a 1000mL glass beaker, add 800mL of deionized water and fully dissolve them to obtain a mixed solution of sodium hydroxide and sodium sulfite; place the softened balsa wood with a thickness of 1mm in the mixed solution of sodium hydroxide and sodium sulfite and ensure that the solution completely immerses the sample, seal the glass beaker with plastic wrap and keep it in a water bath at 100°C for 3 hours, take out the balsa wood and wash it 3 times with deionized water to obtain sample A;

[0069] S2. Take 16 g of sodium chlorite and 400 mL of deionized water and place them in a 1000 mL glass beaker to dissolve them fully to obtain a sodium chlorite solution. Adjust its pH value to 4. Then place sample A in this solution and ensure that the solution completely submerges the sample. Seal the glass beaker with plastic wrap and keep it in a water bath at 80 °C for 1 hour. Take out the balsa wood and wash it 3 times with deionized water;

[0070] (2) Freeze-drying: Keep the pretreated balsa wood sample at -18 °C for 30 minutes, and then put it into a freeze-dryer at -25 °C for 12 hours to obtain a dried wood sample with partial lignin and hemicellulose removed (denoted as delignified wood);

[0071] (3) Vacuum impregnation with gelatin: Dissolve 3 g of gelatin in 100 mL of deionized water and stir it in a water bath at 60 °C for 10 minutes until all the gelatin is dissolved. Place the obtained gelatin solution and the prepared dried wood sample in a vacuum device (-0.8 MPa) for impregnation for 0.5 hour. Take out the sample after the vacuum impregnation and lay it flat to dry naturally to obtain a transparent wood film based on vacuum impregnated wood with gelatin.

[0072] The transparency of the wood film prepared by this method is 8.6%, and the tensile strength is 200.2 MPa.

[0073] Example 3

[0074] A preparation method of a transparent wood film based on vacuum impregnated wood with gelatin, comprising the following steps:

[0075] (1) Pretreatment:

[0076] S1. Cut the balsa wood (raw wood) into 4 cm × 4 cm × 1 mm thin slices and soak them in deionized water for 12 hours to soften. Take 80 g of sodium hydroxide and 32 g of sodium sulfite and place them in a 1000 mL glass beaker, add 800 mL of deionized water and dissolve them fully to obtain a mixed solution of sodium hydroxide and sodium sulfite. Place the softened balsa wood with a thickness of 1 mm in the mixed solution of sodium hydroxide and sodium sulfite and ensure that the solution completely submerges the sample. Seal the glass beaker with plastic wrap and keep it in a water bath at 100 °C for 5 hours. Take out the balsa wood and wash it 3 times with deionized water to obtain sample A;

[0077] S2. Take 16 g of sodium chlorite and 400 mL of deionized water and place them in a 1000 mL glass beaker to dissolve them fully to obtain a sodium chlorite solution. Adjust its pH value to 4. Then place sample A in this solution and ensure that the solution completely submerges the sample. Seal the glass beaker with plastic wrap and keep it in a water bath at 80 °C for 3 hours. Take out the balsa wood and wash it 3 times with deionized water;

[0078] (2) Freeze-drying: The pretreated balsa wood samples were stored frozen at -18°C for 30 minutes, and then placed in a freeze-dryer at -25°C for 12 hours to obtain dry wood samples with partial removal of lignin and hemicellulose (denoted as delignified wood).

[0079] (3) Vacuum impregnation with gelatin: 4 g of gelatin was dissolved in 100 mL of deionized water and stirred in a 60°C water bath for 10 minutes until the gelatin was completely dissolved. The obtained gelatin solution and the prepared dry wood samples were placed in a vacuum device (-0.8 MPa) for impregnation for 0.5 hours. After the vacuum impregnation was completed, the samples were taken out and laid flat to dry naturally to obtain a transparent wood film based on vacuum-impregnated wood with gelatin.

[0080] The transparency of the wood film prepared by this method was 8.6%, and the tensile strength was 83.8 MPa.

[0081] Comparative Example 1

[0082] Same as Example 1, except that the specific steps of step (3) were as follows: 3 g of gelatin was dissolved in 100 mL of deionized water and stirred in a 60°C water bath for 10 minutes until the gelatin was completely dissolved. The prepared dry wood samples were placed in the gelatin solution for impregnation for 0.5 hours. After the impregnation was completed, the samples were taken out and laid flat to dry naturally to obtain a wood film.

[0083] The transparency of the wood film prepared by this method was 2.8%, and the tensile strength was 65 MPa.

[0084] Comparative Example 2

[0085] Same as Example 1, except that step (2) was not carried out.

[0086] The transparency of the wood film prepared by this method was 2.3%, and the tensile strength was 94.2 MPa.

[0087] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for preparing a transparent wood film based on vacuum impregnation of wood with gelatin, characterized in that: The following steps are involved: Pre-treating the wood to obtain a skeleton material retaining porous cellulose; The skeleton material is freeze-dried, then vacuum-impregnated in a gelatin solution, and laid flat to dry naturally, so as to obtain a transparent wood film based on the wood vacuum-impregnated with gelatin.

2. The method for preparing a transparent wood film based on gelatin vacuum impregnation of wood according to claim 1, characterized in that: The pretreatment includes pretreatment with a mixed solution of sodium hydroxide and sodium sulfite and pretreatment with a sodium chlorite solution.

3. The method for preparing a transparent wood film based on gelatin vacuum impregnation of wood according to claim 2, characterized in that: The specific steps of pretreatment with a mixed solution of sodium hydroxide and sodium sulfite include: Cutting the wood into thin slices and soaking them in deionized water for softening to obtain softened wood slices; Dissolving sodium hydroxide and sodium sulfite in deionized water to obtain a mixed solution; The wood pieces are immersed in the mixed solution and heated in a water bath. The wood pieces are taken out and washed with deionized water to obtain semi-pretreated samples.

4. The method for preparing a transparent wood film based on gelatin vacuum impregnation of wood according to claim 3, characterized in that: The cutting size is: 4cm×4cm×1mm; and / or The softening treatment time is 12 hours; and / or In the process of preparing the mixed solution, the usage ratio of the sodium hydroxide, sodium sulfite and deionized water is 1 g: 0.4 g: 10 mL; and / or The water bath heating condition is: water bath heating at 100° C. for 3-5 hours; and / or The washing times are 3 times.

5. The method for preparing a transparent wood film based on gelatin vacuum impregnation of wood according to claim 2, characterized in that: The specific steps of pretreatment with sodium chlorite solution include: Dissolving sodium chlorite in deionized water and adjusting the pH to acidic to obtain a sodium chlorite solution; The sample obtained by pretreatment with the mixed solution of sodium hydroxide and sodium sulfite is immersed in the sodium chlorite solution, and the water bath heating is continued. The wood pieces are taken out and washed with deionized water, and the pretreatment is completed.

6. The method for preparing a transparent wood film based on vacuum impregnation of wood with gelatin according to claim 5, characterized in that: In the process of preparing the sodium chlorite solution, the usage ratio of the sodium chlorite to deionized water is 1 g: 25 mL; and / or The pH value is 4; and / or The conditions for continuing water bath heating are: heating in a water bath at 80° C. for 1-3 hours; and / or The washing times were all 3 times.

7. The method for preparing a transparent wood film based on gelatin vacuum impregnation of wood according to claim 1, characterized in that: The freeze-drying conditions are: freeze-store at -18°C for 30 minutes, and then place in a -25°C freeze dryer for 12 hours.

8. The method for preparing a transparent wood film based on vacuum impregnation of wood with gelatin according to claim 1, characterized in that: The vacuum impregnation conditions are: vacuum impregnation at -0.8 MPa for 0.5 hours.

9. The method for preparing a transparent wood film based on vacuum impregnation of wood with gelatin according to claim 1, characterized in that: The preparation process of the gelatin solution is as follows: gelatin is added into deionized water, and stirred for 10 minutes in a 60° C. water bath to obtain the gelatin solution; wherein the usage ratio of gelatin to deionized water is (1-5) g: 100 mL.

10. A transparent wood film based on wood vacuum impregnated with gelatin prepared by the preparation method according to any one of claims 1 to 9.

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