CN-118617522-B - Super-strong wooden film and preparation method thereof

Abstract

The invention discloses a super-strong wood film and a preparation method thereof, wherein the wood film has a compact structure composed of nanofibers of wood cell walls and regenerated cellulose, nanofiber bundles are uniformly distributed in cell cavities, and the periphery of each nanofiber bundle is surrounded by the regenerated cellulose; the preparation method comprises the following steps of immersing the wood thin sheet into lignin removing solution for full reaction, then treating wood fibers by using chemical solution, washing after full pouring reaction, and naturally drying and shrinking to obtain the super-strong wood thin film. The super-strong wood film prepared by adopting the top-down method has various advantages of high mechanical strength (the longitudinal tensile strength is 600-900 MPa), good optical performance and stronger flexibility, can realize the splicing treatment of length and width, and basically keeps the strength of the spliced wood film unchanged without separation at a bonding part.

Inventors

• ZHU MINGWEI
• CAO ZHIRU
• HUANG ZHONGLEI
• CHEN YANFENG

Assignees

• 南京大学

Dates

Publication Date

20260508

Application Date

20240613

Claims (9)

1. 1. The super-strong wood film is characterized by having a compact structure composed of nanofibers of wood cell walls and regenerated cellulose, wherein the nanofiber bundles are uniformly distributed in a cell cavity, and the periphery of each nanofiber bundle is surrounded by the regenerated cellulose, and the preparation method of the super-strong wood film comprises the following steps: Immersing the wood sheet into a treatment solution A for lignin removal, wherein the treatment solution A is at least one of a strong alkali solution, a hydrogen peroxide solution, a sodium hypochlorite solution and a sodium hydroxide/sodium sulfite solution; Immersing the treated wood flake into a B treatment solution for swelling treatment, wherein the B treatment solution is at least one of an alkali/urea mixed solution, a lithium chloride/N.N dimethylacetamide solution, an N-methylmorpholine-N-oxide solution, an ion solution and a cuprammonium solution; And (3) fully pouring a C treatment solution into the wood sheet obtained after the swelling treatment, filling the gaps among wood cells with the pouring solution, and washing and drying to obtain the super-strong wood film, wherein the C treatment solution is at least one of a cellulose powder solution, a ramie cellulose solution and a cotton cellulose solution.
2. 2. The super strong wood film according to claim 1, wherein the wood film has a thickness of 10 to 200 μm and a density of 1.4 to 1.8g cm -3 .
3. 3. The super strong wood film according to claim 1, wherein the wood film has a grain-oriented tensile strength of 600 to 900mpa.
4. 4. The super strong wood film according to claim 1, wherein the splicing treatment of the length and the width can be realized, and the strength of the spliced wood film is not lower than 95% of the original strength.
5. 5. The super strong wood film according to claim 1, wherein the wood film has a transparency of up to 90% and a haze of 50 to 90%.
6. 6. The super strong wood film according to claim 1, wherein the wood flakes are treated in the treatment solution a at a temperature of 50 ℃ to 100 ℃ for 30min to 10h.
7. 7. The super strong wood film according to claim 1, wherein the time for the treated wood flakes to fully react in the B treatment solution is 30min to 24h.
8. 8. The super-strong wood film according to claim 1, wherein the mass concentration of the C treatment solution is 0.1% -10%, and the treatment time is 1-24 hours.
9. 9. The super strong wood film according to claim 1, wherein the pouring is performed by vacuum or suction filtration.

Description

Super-strong wooden film and preparation method thereof Technical Field The invention relates to an ecological material and a preparation method thereof, in particular to a super-strong wood film and a preparation method thereof. Background The film material is a high and new technology material widely applied in various industrial fields, including but not limited to plastic films, metal films, glass films and ceramic films. The film material is an important material form, has a plurality of excellent properties such as high light transmittance, high strength, high toughness, high plasticity, high barrier property, high heat preservation and the like, and the superior properties lead the film material to be widely applied in the industries of building traffic, aerospace, medical building materials, energy sources, electronics and the like, and to represent a rapidly developed situation in the global scope. However, the film materials of the types have the problems of high cost, difficult degradation, serious waste pollution and the like, and particularly in recent years, the environmental problem is concerned by various social circles, so that the substitute of the existing film materials is searched, and the development of the film new material which is completely biodegradable, environment-friendly and renewable, low in cost and excellent in performance has great scientific value and social significance. The natural fiber material, especially wood, has excellent mechanical property as one kind of renewable resource, and its microstructure presents complicated hierarchical structure and ordered fiber structure, so that it has excellent mechanical strength, tensile strength and biocompatibility. The nano fiber in the wood hierarchical structure is considered as a new generation of high-performance fiber, the theoretical strength is in the same order of magnitude as that of the carbon fiber and the glass fiber, and the nano fiber is transparent, light and environment-friendly, which means that the performance of natural materials such as wood and the like has great lifting potential and space in the fields of aerospace, medical traffic and the like, and simultaneously meets the requirement of sustainable development. In the prior art, a wood film is mostly prepared in a bottom-up mode, wood cellulose is prepared into a film by using a wood cell dissolution regeneration process and adopting methods such as suction filtration, mould pressing, self-assembly and the like, the wood film is isotropic and high in transparency, but the preparation steps are complicated, especially the process of dissolving wood macromolecules into nano-scale cellulose is complex, large-scale industrial production is difficult to realize, and meanwhile, the wood film has the defects of low mechanical strength, high molding difficulty and the like due to strong brittleness. Meanwhile, the conventional film material is difficult to sacrifice transparency and has high strength, for example, CN 117901219A discloses a wood-based film, the surface of which is coated with a plant fiber mixed solution after wood chips are delignified, and the formed wood-based film has low transparency. Disclosure of Invention The invention aims to provide a super-strong wood film with high strength and excellent optical performance, and also aims to provide a preparation method of the super-strong wood film. According to the technical scheme, the super-strong wood film has a compact structure composed of nano fibers and regenerated cellulose on the cell wall of wood, wherein nano fiber bundles are uniformly distributed in a cell cavity, the periphery of each nano fiber bundle is surrounded by the regenerated cellulose, and the wood cells are in a solid column shape. Preferably, the thickness of the super-strong wood film is 10-200 mu m, the density is 1.4-1.8 g cm -3, and the lignin content is 10% -90%. Preferably, the stretch strength of the super-strong wood film along the grain is 600-900 MPa. The high-strength wood film is obtained by fully pouring cellulose solution after fiber swelling is realized by treating wood chip chemical reagent with partial lignin removal, and naturally drying and shrinking. The fiber is uniformly dispersed in the whole cell cavity after swelling treatment, large-size holes are basically disappeared, certain intervals are generated among the fibers, single wood cells are in column units with gaps, further infused cellulose solution is filled into the cell cavities uniformly distributed among the fibers and surrounds nanofiber bundles in the cavities, the effect of reinforcing and toughening is achieved by greatly increasing the hydrogen bond density among cellulose chains, the breakthrough improvement of the mechanical property of the wood film is realized, and the wood cells are contracted, the film thickness is reduced and the strength is again improved after drying treatment under certain conditions. Preferably, the super-